Flip, move, pan, zoom in, zoom out
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- var canvas = document.getElementById('canvas');
- if (canvas.getContext) {
-
var context = canvas.getContext('2d');
- // 放大与缩小
- context.beginPath();
-
context.strokeStyle = "#000000";
- context.strokeRect(10,10,150,100);
-
- // 放大3倍
- context.scale(3,3);
- context.beginPath();
-
context.strokeStyle = '#cccccc';
- context.strokeRect(10,10,150,100)
-
- // 缩小
- context.scale(0.5,0.5);
- context.beginPath();
-
context.strokeStyle = '#cccccc';
- context.strokeRect(10,10,150,100)
-
- // 翻转
-
var img = new Image();
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img.src = 'images/1.jpg';
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img.onload = function(){
- context.drawImage(img, 10,10);
- context.scale(1, -1);
- context.drawImage(img, 0, -500);
- }
- // 平移
- context.beginPath();
-
context.strokeStyle = '#000000';
- context.strokeRect(10,101,150,100);
- // x移动 50 y 移动100
- context.translate(50,100);
- context.beginPath();
-
context.strokeStyle = '#cccccc';
- context.strokeRect(10,10,150,100);
- // 旋转
- context.beginPath();
-
context.strokeStyle = '#000000';
- context.strokeRect(200,50,100,50);
- // 默认旋转是根据0,0中心,使用translate可以按照自己的设置的中心旋转
- context.translate(250,75);
-
- context.rotate(45 * Math.PI /180);
- context.translate(-250, -75);
-
- context.beginPath();
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context.strokeStyle = '#cccccc';
- context.strokeRect(200,50,100,50);
-
- // transform 矩阵
- context.beginPath();
-
context.strokeStyle = '#000000';
- context.strokeRect(10,10,150,100);
-
- context.transform(3,0,0,3,0,0);
- context.beginPath();
-
context.strokeStyle = '#cccccc';
- context.strokeRect(10,10,150,100);
-
- }
渐变、图像组合效果、颜色翻转
XML/HTML Code复制内容到剪贴板
- var canvas = document.getElementById('canvas');
- if (canvas.getContext) {
-
var context = canvas.getContext('2d');
- // Linear drawing gradient
-
var grd = context.createLinearGradient(0,0,200,100);
- // position must be vertical between 0.1-1.0, indicating the relative position of the color in the gradient, color represents the color
- grd.addColorStop(0.1, "#00ff00");
- grd.addColorStop(0.8, "#ff0000");
-
-
context.fillStyle = grd;
- context.fillRect(0,0, 200,100);
- // Radial gradient
-
var grd = context.createRadialGradient(100,100,10,100,100,50);
- grd.addColorStop(0.1, "#00ff00");
- grd.addColorStop(0.8, '#ff0000');
-
context.fillStyle = grd;
- context.fillRect(0,0,200,200);
- // Image combination effect
-
context.fillStyle = '#00ff00';
- context.fillRect(10,10,50,50);
- // New drawing
-
//context.globalCompositeOperation = "source-over";
- // Only draw new content, delete all other content
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context.globalCompositeOperation = 'copy';
- // Where graphics overlap, the color values are subtracted to determine
-
context.globalCompositeOperation = 'darker';
- // The content already on the canvas will only be retained where it overlaps with other graphics
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context.globalCompositeOperation = 'destination-atop';
- // Reference http://www.w3school.com.cn/htmldom/prop_canvasrenderingcontext2d_globalcompositeoperation.asp
- context.beginPath();
-
context.fillStyle = '#ff0000';
- context.arc(50,50,30,0, 2 * Math.PI);
- context.fill();
-
- // 颜色翻转
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var img = new Image();
-
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img.src = 'images/1.jpg';
-
img.onload = function(){
- context.drawImage(img, 0,0, 1, 1);
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var imgData = context.getImageData(0,0, 1,1);
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var pixels = imgData.data;
- console.log(pixels);
-
for(var i = 0, n = pixels.length; i < n; i =4) {
- pixels[i] = 255 - pixels[i];
- pixels[i 1] = 255 - pixels[i 1];
- pixels[i 2] = 255 - pixels[i 2];
- }
- context.putImageData(imgData, 250, 0);
- }
- }