CanvasPattern.setTransform() 方法使用 {{domxref("SVGMatrix")}} 对象作为图案的变换矩阵，并在此图案上调用它。
void pattern.setTransform(matrix);
matrixsetTransform 方法这是一段简单的代码片段，使用 setTransform 方法创建一个来自 {{domxref("SVGMatrix")}} 具有指定图案变化的{{domxref("CanvasPattern")}} 。如例子所示，如果你把图案赋值给当前的 {{domxref("CanvasRenderingContext2D.fillStyle", "fillStyle")}} ，当你使用 {{domxref("CanvasRenderingContext2D.fillRect", "fillRect()")}} 方法时，图案会被应用到 canvas 上绘制出效果。
<canvas id="canvas"></canvas> <svg id="svg1"></svg>
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var svg1 = document.getElementById("svg1");
var matrix = svg1.createSVGMatrix();
var img = new Image();
img.src = 'https://mdn.mozillademos.org/files/222/Canvas_createpattern.png';
img.onload = function() {
var pattern = ctx.createPattern(img, 'repeat');
pattern.setTransform(matrix.rotate(-45).scale(1.5));
ctx.fillStyle = pattern;
ctx.fillRect(0,0,400,400);
};
修改下面的代码并在线查看 canvas 的变化：
<canvas id="canvas" width="400" height="200" class="playable-canvas"></canvas>
<svg id="svg1" style="display:none"></svg>
<div class="playable-buttons">
<input id="edit" type="button" value="Edit" />
<input id="reset" type="button" value="Reset" />
</div>
<textarea id="code" class="playable-code" style="height:120px">
var img = new Image();
img.src = 'https://mdn.mozillademos.org/files/222/Canvas_createpattern.png';
img.onload = function() {
var pattern = ctx.createPattern(img, 'repeat');
pattern.setTransform(matrix.rotate(-45).scale(1.5));
ctx.fillStyle = pattern;
ctx.fillRect(0,0,400,400);
};</textarea>
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var textarea = document.getElementById("code");
var reset = document.getElementById("reset");
var edit = document.getElementById("edit");
var code = textarea.value;
var svg1 = document.getElementById("svg1");
var matrix = svg1.createSVGMatrix();
function drawCanvas() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
eval(textarea.value);
}
reset.addEventListener("click", function() {
textarea.value = code;
drawCanvas();
});
edit.addEventListener("click", function() {
textarea.focus();
})
textarea.addEventListener("input", drawCanvas);
window.addEventListener("load", drawCanvas);
{{ EmbedLiveSample('Playable_code', 700, 380) }}
| Specification | Status | Comment |
|---|---|---|
| {{SpecName('HTML WHATWG', "scripting.html#dom-canvaspattern-settransform", "CanvasPattern.setTransform")}} | {{Spec2('HTML WHATWG')}} |