From 074785cea106179cb3305637055ab0a009ca74f2 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:42:52 -0500 Subject: initial commit --- .../web/api/canvasrenderingcontext2d/index.html | 450 +++++++++++++++++++++ 1 file changed, 450 insertions(+) create mode 100644 files/pt-br/web/api/canvasrenderingcontext2d/index.html (limited to 'files/pt-br/web/api/canvasrenderingcontext2d/index.html') diff --git a/files/pt-br/web/api/canvasrenderingcontext2d/index.html b/files/pt-br/web/api/canvasrenderingcontext2d/index.html new file mode 100644 index 0000000000..38ec19a3e3 --- /dev/null +++ b/files/pt-br/web/api/canvasrenderingcontext2d/index.html @@ -0,0 +1,450 @@ +--- +title: 'Canvas: Contexto de Renderização em "2D"' +slug: Web/API/CanvasRenderingContext2D +tags: + - API + - Canvas + - CanvasRenderingContext2D + - Games + - Graphics + - NeedsTranslation + - Reference + - TopicStub +translation_of: Web/API/CanvasRenderingContext2D +--- +
{{APIRef}}
+ +
A interface Canvas Renderização de Contexto de duas Dimensões ( CanvasRenderingContext2D) é usada para desenhar retangulos, textos, imagens e outros objetos na tag ou elemento canvas. Fornece o contexto de renderização em 2D para a superfície de desenho do elemento  {{ HTMLElement("canvas") }}.
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Para obter um objeto desta interface, chama-se  {{domxref("HTMLCanvasElement.getContext()", "getContext()")}} em um elemento <canvas>, adicionando "2d" como argumento, veja o exemplo abaixo:

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var canvas = document.getElementById('meuCanvas'); // em seu HTML esse elemento se parece com <canvas id="meuCanvas"></canvas>
+var ctx = canvas.getContext('2d');
+
+ +

Agora que você possui o contexto de renderização 2D, você pode desenhar dentro deste canvas. Por exemplo:

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ctx.fillStyle = "rgb(200,0,0)"; // define a cor de preenchimento do retângulo
+ctx.fillRect(10, 10, 55, 50);   // desenha o retângulo na posição 10, 10 com 55 pixels de largura e uma altura de 50
+
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Veja as propriedades e métodos no menu lateral e abaixo. O tutorial canvas tem mais informações, exemplos e recursos.

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Desenhando Retângulos

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Existem três métodos que imediatamente desenham retângulos ao canvas.

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{{domxref("CanvasRenderingContext2D.clearRect()")}}
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Determina todos os pixels no retângulo definido, pelo ponto inicial (x, y) e tamanho (largura, altura) para preto transparente, apagando qualquer conteúdo desenhado anteriormente.
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{{domxref("CanvasRenderingContext2D.fillRect()")}}
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Desenha um retângulo preenchido na posição (x, y) com tamanho definido pela largura e altura
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{{domxref("CanvasRenderingContext2D.strokeRect()")}}
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Pinta um retângulo o qual possui um ponto inicial em (x, y) e possui um w width(largura) e um h height(altura) dentro da tela(canvas), usando o estilo de traçado(stroke) atual.
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Desenhando Textos

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Os métodos seguintes são fornecidos para desenhar texto. Veja também o objeto {{domxref("TextMetrics")}} para propriedades de texto.

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{{domxref("CanvasRenderingContext2D.fillText()")}}
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Desenha(preenche) um texto fornecido, em uma posição fornecida(x,y).
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{{domxref("CanvasRenderingContext2D.strokeText()")}}
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Desenha(traçados) um texto fornecido, em uma posição fornecida(x,y).
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{{domxref("CanvasRenderingContext2D.measureText()")}}
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Retorna um objeto {{domxref("TextMetrics")}} .
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Estilos de linha

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Os seguintes métodos e propriedades, controlam como as linhas são desenhadas.

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{{domxref("CanvasRenderingContext2D.lineWidth")}}
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Largura das linhas. Padrão: 1.0
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{{domxref("CanvasRenderingContext2D.lineCap")}}
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Tipos de pontas no final das linhas. Valores possíveis: butt (padrão), round, square.
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{{domxref("CanvasRenderingContext2D.lineJoin")}}
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Define o tipo de encontro entre duas linhas. Possíveis valores: round, bevel, miter (default).
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{{domxref("CanvasRenderingContext2D.miterLimit")}}
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Relação do limite de esquadria. Padrão: 10.
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{{domxref("CanvasRenderingContext2D.getLineDash()")}}
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Retorna a matriz de padrão de traço de linha atual contendo um número par de números não negativos.
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{{domxref("CanvasRenderingContext2D.setLineDash()")}}
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Define o padrão de traço de linha atual.
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{{domxref("CanvasRenderingContext2D.lineDashOffset")}}
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Especifica onde iniciar uma matriz de traços em uma linha.
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Estilos de textos

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As propriedades abaixo controlam a estilização do texto a ser apresentado:

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{{domxref("CanvasRenderingContext2D.font")}}
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Configuração da fonte. Valor padrão: 10px sans-serif.
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{{domxref("CanvasRenderingContext2D.textAlign")}}
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Alinhamento do texto. Possíveis valores: start (padrão), end, left, right or center.
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{{domxref("CanvasRenderingContext2D.textBaseline")}}
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Configuração de alinhamento da linha de base (Baseline). Possíveis valores: top, hanging, middle, alphabetic (padrão), ideographic, bottom.
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{{domxref("CanvasRenderingContext2D.direction")}}
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Direção do texto. Possívels valores: ltr, rtl, inherit (padrão).
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Estilos de preenchimento e traço

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O estilo de preenchimento é usado para cores e estilos dentro das formas e o estilo de traço é usado para as linhas ao redor das formas.

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{{domxref("CanvasRenderingContext2D.fillStyle")}}
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Cor ou estilo para usar formas internas. Padrão #000 (preto).
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{{domxref("CanvasRenderingContext2D.strokeStyle")}}
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Cor ou estilo a ser usado para as linhas em torno das formas. Padrão: #000 (preto).
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Gradientes e padrões

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{{domxref("CanvasRenderingContext2D.createLinearGradient()")}}
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Cria um gradiente linear ao longo da linha fornecida pelas coordenadas representadas pelos parâmetros.
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{{domxref("CanvasRenderingContext2D.createRadialGradient()")}}
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Cria um gradiente radial dado pelas coordenadas dos dois círculos representados pelos parâmetros.
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{{domxref("CanvasRenderingContext2D.createPattern()")}}
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Cria um padrão usando a imagem especificada (uma {{domxref("CanvasImageSource")}}). Ele repete a fonte nas direções especificadas pelo argumento de repetição. Este método retorna um {{domxref("CanvasPattern")}}.
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Sombras

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{{domxref("CanvasRenderingContext2D.shadowBlur")}}.
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Especifica o efeito de desfoque. Padrão: 0.
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{{domxref("CanvasRenderingContext2D.shadowColor")}}
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Cor da sombra. Padrão: fully-transparent black (preto totalmente transparente).
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{{domxref("CanvasRenderingContext2D.shadowOffsetX")}}
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Distância horizontal em que a sombra será deslocada. Padrão: 0.
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{{domxref("CanvasRenderingContext2D.shadowOffsetY")}}
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Distância vertical em que a sombra será deslocada. Padrão: 0.
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Caminhos

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Os seguintes métodos podem ser usados para manipular caminhos de desenhos.

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{{domxref("CanvasRenderingContext2D.beginPath()")}}
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Inicia um novo caminho esvaziando a lista de subcaminhos. Chame esse método quando você quiser criar um novo caminho.
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{{domxref("CanvasRenderingContext2D.closePath()")}}
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Faz com que a ponta da caneta se mova de volta para o início do subcaminho atual. Ele tenta traçar uma linha reta do ponto atual ao início. Se o desenho já foi fechado ou tem apenas um ponto, este método não faz nada.
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{{domxref("CanvasRenderingContext2D.moveTo()")}}
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Move o ponto inicial de um novo subcaminho para as coordenadas (x, y).
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{{domxref("CanvasRenderingContext2D.lineTo()")}}
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Conecta o último ponto do caminho atual com as coordenadas (x, y) com linha reta.
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{{domxref("CanvasRenderingContext2D.bezierCurveTo()")}}
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Adiciona uma curva de Bézier ao caminho atual.
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{{domxref("CanvasRenderingContext2D.quadraticCurveTo()")}}
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Adiciona uma curva de Bézier quadrática ao caminho atual.
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{{domxref("CanvasRenderingContext2D.arc()")}}
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Adiciona um arco circular ao caminho atual.
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{{domxref("CanvasRenderingContext2D.arcTo()")}}
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Adiciona um arco no caminho atual com os pontos de controle e raio fornecidos, conectado ao ponto anterior por uma linha reta.
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{{domxref("CanvasRenderingContext2D.ellipse()")}}
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Adiciona um arco elíptico ao caminho atual.
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{{domxref("CanvasRenderingContext2D.rect()")}}
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Cria um caminho de retângulo na posição (x, y) com o tamanho determinado por width e height.
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Drawing paths

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{{domxref("CanvasRenderingContext2D.fill()")}}
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Fills the subpaths with the current fill style.
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{{domxref("CanvasRenderingContext2D.stroke()")}}
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Strokes the subpaths with the current stroke style.
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{{domxref("CanvasRenderingContext2D.drawFocusIfNeeded()")}}
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If a given element is focused, this method draws a focus ring around the current path.
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{{domxref("CanvasRenderingContext2D.scrollPathIntoView()")}}
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Scrolls the current path or a given path into the view.
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{{domxref("CanvasRenderingContext2D.clip()")}}
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Creates a clipping path from the current sub-paths. Everything drawn after clip() is called appears inside the clipping path only. For an example, see Clipping paths in the Canvas tutorial.
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{{domxref("CanvasRenderingContext2D.isPointInPath()")}}
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Reports whether or not the specified point is contained in the current path.
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{{domxref("CanvasRenderingContext2D.isPointInStroke()")}}
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Reports whether or not the specified point is inside the area contained by the stroking of a path.
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Transformações

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Objects in the CanvasRenderingContext2D rendering context have a current transformation matrix and methods to manipulate it. The transformation matrix is applied when creating the current default path, painting text, shapes and {{domxref("Path2D")}} objects. The methods listed below remain for historical and compatibility reasons as {{domxref("SVGMatrix")}} objects are used in most parts of the API nowadays and will be used in the future instead.

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{{domxref("CanvasRenderingContext2D.currentTransform")}}
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Current transformation matrix ({{domxref("SVGMatrix")}} object).
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{{domxref("CanvasRenderingContext2D.rotate()")}}
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Adds a rotation to the transformation matrix. The angle argument represents a clockwise rotation angle and is expressed in radians.
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{{domxref("CanvasRenderingContext2D.scale()")}}
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Adds a scaling transformation to the canvas units by x horizontally and by y vertically.
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{{domxref("CanvasRenderingContext2D.translate()")}}
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Adds a translation transformation by moving the canvas and its origin x horzontally and y vertically on the grid.
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{{domxref("CanvasRenderingContext2D.transform()")}}
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Multiplies the current transformation matrix with the matrix described by its arguments.
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{{domxref("CanvasRenderingContext2D.setTransform()")}}
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Resets the current transform to the identity matrix, and then invokes the transform() method with the same arguments.
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{{domxref("CanvasRenderingContext2D.resetTransform()")}} {{experimental_inline}}
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Resets the current transform by the identity matrix.
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Compositing

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{{domxref("CanvasRenderingContext2D.globalAlpha")}}
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Alpha value that is applied to shapes and images before they are composited onto the canvas. Default 1.0 (opaque).
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{{domxref("CanvasRenderingContext2D.globalCompositeOperation")}}
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With globalAlpha applied this sets how shapes and images are drawn onto the existing bitmap.
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Desenhando imagens

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{{domxref("CanvasRenderingContext2D.drawImage()")}}
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Draws the specified image. This method is available in multiple formats, providing a great deal of flexibility in its use.
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Manipulação de pixels

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See also the {{domxref("ImageData")}} object.

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{{domxref("CanvasRenderingContext2D.createImageData()")}}
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Creates a new, blank {{domxref("ImageData")}} object with the specified dimensions. All of the pixels in the new object are transparent black.
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{{domxref("CanvasRenderingContext2D.getImageData()")}}
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Returns an {{domxref("ImageData")}} object representing the underlying pixel data for the area of the canvas denoted by the rectangle which starts at (sx, sy) and has an sw width and sh height.
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{{domxref("CanvasRenderingContext2D.putImageData()")}}
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Paints data from the given {{domxref("ImageData")}} object onto the bitmap. If a dirty rectangle is provided, only the pixels from that rectangle are painted.
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Image smoothing

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{{domxref("CanvasRenderingContext2D.imageSmoothingEnabled")}} {{experimental_inline}}
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Image smoothing mode; if disabled, images will not be smoothed if scaled.
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The canvas state

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The CanvasRenderingContext2D rendering context contains a variety of drawing style states (attributes for line styles, fill styles, shadow styles, text styles). The following methods help you to work with that state:

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{{domxref("CanvasRenderingContext2D.save()")}}
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Saves the current drawing style state using a stack so you can revert any change you make to it using restore().
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{{domxref("CanvasRenderingContext2D.restore()")}}
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Restores the drawing style state to the last element on the 'state stack' saved by save().
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{{domxref("CanvasRenderingContext2D.canvas")}}
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A read-only back-reference to the {{domxref("HTMLCanvasElement")}}. Might be {{jsxref("null")}} if it is not associated with a {{HTMLElement("canvas")}} element.
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Hit regions

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{{domxref("CanvasRenderingContext2D.addHitRegion()")}} {{experimental_inline}}
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Adds a hit region to the canvas.
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{{domxref("CanvasRenderingContext2D.removeHitRegion()")}} {{experimental_inline}}
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Removes the hit region with the specified id from the canvas.
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{{domxref("CanvasRenderingContext2D.clearHitRegions()")}} {{experimental_inline}}
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Removes all hit regions from the canvas.
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Non-standard APIs

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Most of these APIs are deprecated and will be removed in the future.

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{{non-standard_inline}} CanvasRenderingContext2D.clearShadow()
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Removes all shadow settings like {{domxref("CanvasRenderingContext2D.shadowColor")}} and {{domxref("CanvasRenderingContext2D.shadowBlur")}}.
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{{non-standard_inline}} CanvasRenderingContext2D.drawImageFromRect()
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This is redundant with an equivalent overload of drawImage.
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{{non-standard_inline}} CanvasRenderingContext2D.setAlpha()
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Use {{domxref("CanvasRenderingContext2D.globalAlpha")}} instead.
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{{non-standard_inline}} CanvasRenderingContext2D.setCompositeOperation()
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Use {{domxref("CanvasRenderingContext2D.globalCompositeOperation")}} instead.
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{{non-standard_inline}} CanvasRenderingContext2D.setLineWidth()
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Use {{domxref("CanvasRenderingContext2D.lineWidth")}} instead.
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{{non-standard_inline}} CanvasRenderingContext2D.setLineJoin()
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Use {{domxref("CanvasRenderingContext2D.lineJoin")}} instead.
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{{non-standard_inline}} CanvasRenderingContext2D.setLineCap()
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Use {{domxref("CanvasRenderingContext2D.lineCap")}} instead.
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{{non-standard_inline}} CanvasRenderingContext2D.setMiterLimit()
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Use {{domxref("CanvasRenderingContext2D.miterLimit")}} instead.
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{{non-standard_inline}} CanvasRenderingContext2D.setStrokeColor()
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Use {{domxref("CanvasRenderingContext2D.strokeStyle")}} instead.
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{{non-standard_inline}} CanvasRenderingContext2D.setFillColor()
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Use {{domxref("CanvasRenderingContext2D.fillStyle")}} instead.
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{{non-standard_inline}} CanvasRenderingContext2D.setShadow()
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Use {{domxref("CanvasRenderingContext2D.shadowColor")}} and {{domxref("CanvasRenderingContext2D.shadowBlur")}} instead.
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{{non-standard_inline}} CanvasRenderingContext2D.webkitLineDash
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Use {{domxref("CanvasRenderingContext2D.getLineDash()")}} and {{domxref("CanvasRenderingContext2D.setLineDash()")}} instead.
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{{non-standard_inline}} CanvasRenderingContext2D.webkitLineDashOffset
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Use {{domxref("CanvasRenderingContext2D.lineDashOffset")}} instead.
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{{non-standard_inline}} CanvasRenderingContext2D.webkitImageSmoothingEnabled
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Use {{domxref("CanvasRenderingContext2D.imageSmoothingEnabled")}} instead.
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{{non-standard_inline}} CanvasRenderingContext2D.getContextAttributes()
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Inspired by the same WebGLRenderingContext method it returns an Canvas2DContextAttributes object that contains the attributes "storage" to indicate which storage is used ("persistent" by default) and the attribute "alpha" (true by default) to indicate that transparency is used in the canvas.
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{{non-standard_inline}} CanvasRenderingContext2D.isContextLost()
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Inspired by the same WebGLRenderingContext method it returns true if the Canvas context has been lost, or false if not.
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WebKit only

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{{non-standard_inline}} CanvasRenderingContext2D.webkitBackingStorePixelRatio
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The backing store size in relation to the canvas element. See High DPI Canvas.
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{{non-standard_inline}} CanvasRenderingContext2D.webkitGetImageDataHD
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Intended for HD backing stores, but removed from canvas specifications.
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{{non-standard_inline}} CanvasRenderingContext2D.webkitPutImageDataHD
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Intended for HD backing stores, but removed from canvas specifications.
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Gecko only

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{{non-standard_inline}} {{domxref("CanvasRenderingContext2D.filter")}}
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CSS and SVG filters as Canvas APIs. Likely to be standardized in a new version of the specification.
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Prefixed APIs

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{{non-standard_inline}} CanvasRenderingContext2D.mozCurrentTransform
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Sets or gets the current transformation matrix, see {{domxref("CanvasRenderingContext2D.currentTransform")}}.  {{ gecko_minversion_inline("7.0") }}
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{{non-standard_inline}} CanvasRenderingContext2D.mozCurrentTransformInverse
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Sets or gets the current inversed transformation matrix.  {{ gecko_minversion_inline("7.0") }}
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{{non-standard_inline}} CanvasRenderingContext2D.mozFillRule
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The fill rule to use. This must be one of evenodd or nonzero (default).
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{{non-standard_inline}} CanvasRenderingContext2D.mozImageSmoothingEnabled
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See {{domxref("CanvasRenderingContext2D.imageSmoothingEnabled")}}.
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{{non-standard_inline}} {{deprecated_inline}} CanvasRenderingContext2D.mozDash
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An array which specifies the lengths of alternating dashes and gaps {{ gecko_minversion_inline("7.0") }}. Use {{domxref("CanvasRenderingContext2D.getLineDash()")}} and {{domxref("CanvasRenderingContext2D.setLineDash()")}} instead.
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{{non-standard_inline}} {{deprecated_inline}} CanvasRenderingContext2D.mozDashOffset
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Specifies where to start a dash array on a line. {{ gecko_minversion_inline("7.0") }}. Use {{domxref("CanvasRenderingContext2D.lineDashOffset")}} instead.
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{{non-standard_inline}} {{deprecated_inline}} CanvasRenderingContext2D.mozTextStyle
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Introduced in in Gecko 1.9, deprecated in favor of the {{domxref("CanvasRenderingContext2D.font")}} property.
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{{non-standard_inline}} {{obsolete_inline}} CanvasRenderingContext2D.mozDrawText()
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This method was introduced in Gecko 1.9 and is removed starting with Gecko 7.0. Use {{domxref("CanvasRenderingContext2D.strokeText()")}} or {{domxref("CanvasRenderingContext2D.fillText()")}} instead.
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{{non-standard_inline}} {{obsolete_inline}} CanvasRenderingContext2D.mozMeasureText()
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This method was introduced in Gecko 1.9 and is unimplemented starting with Gecko 7.0. Use {{domxref("CanvasRenderingContext2D.measureText()")}} instead.
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{{non-standard_inline}} {{obsolete_inline}} CanvasRenderingContext2D.mozPathText()
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This method was introduced in Gecko 1.9 and is removed starting with Gecko 7.0.
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{{non-standard_inline}} {{obsolete_inline}} CanvasRenderingContext2D.mozTextAlongPath()
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This method was introduced in Gecko 1.9 and is removed starting with Gecko 7.0.
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Internal APIs (chrome-context only)

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{{non-standard_inline}} {{domxref("CanvasRenderingContext2D.asyncDrawXULElement()")}}
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Renders a region of a XUL element into the canvas.
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{{non-standard_inline}} {{domxref("CanvasRenderingContext2D.drawWindow()")}}
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Renders a region of a window into the canvas. The contents of the window's viewport are rendered, ignoring viewport clipping and scrolling.
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{{non-standard_inline}} CanvasRenderingContext2D.demote()
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This causes a context that is currently using a hardware-accelerated backend to fallback to a software one. All state should be preserved.
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Internet Explorer

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{{non-standard_inline}} CanvasRenderingContext2D.msFillRule
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The fill rule to use. This must be one of evenodd or nonzero (default).
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Especificações

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SpecificationStatusComment
{{SpecName('HTML WHATWG', "scripting.html#2dcontext:canvasrenderingcontext2d", "CanvasRenderingContext2D")}}{{Spec2('HTML WHATWG')}}
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Compatibilidade do Navegador

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{{CompatibilityTable}}
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FeatureChromeFirefox (Gecko)Internet ExplorerOperaSafari
Basic support{{CompatChrome("1")}}{{CompatGeckoDesktop("1.8")}}{{CompatIE("9")}}{{CompatOpera("9")}}{{CompatSafari("2")}}
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FeatureAndroidChrome for AndroidFirefox Mobile (Gecko)IE MobileOpera MobileSafari Mobile
Basic support{{CompatUnknown}}{{CompatUnknown}}{{CompatUnknown}}{{CompatUnknown}}{{CompatUnknown}}{{CompatUnknown}}
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Compatibility notes

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Veja também

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