我正在尝试缩放画布图像。这是我正在使用的函数。
<script language="javascript">
$('#zoomin').click(function(){
var canvasWidth=canvas.width;
var canvasHeight=canvas.height;
canvas.width=canvasWidth*1.5;
canvas.height=canvasHeight*1.5;
context.scale(1.5,1.5);
});
</script>
但问题是图片被放大了，但背景图片没有被放大。
请查看这张图片。
更新
这是我的 paint.js 文件。
colorPurple = {
r: 203,
g: 53,
b: 148
};
var colorGreen = {
r: 101,
g: 155,
b: 65
};
var colorYellow = {
r: 255,
g: 207,
b: 51
};
var colorBrown = {
r: 152,
g: 105,
b: 40
};
var context;
canvasWidth = 500;
canvasHeight = 500;
var myColor=colorYellow;
console.log(myColor);
var curColor = myColor;
var outlineImage = new Image();
var swatchImage = new Image();
var backgroundImage = new Image();
var swatchStartX = 18;
var swatchStartY = 19;
var swatchImageWidth = 93;
var swatchImageHeight = 46;
var drawingAreaX = 0;
var drawingAreaY = 0;
var drawingAreaWidth = 500;
var drawingAreaHeight = 500;
var colorLayerData;
var outlineLayerData;
var totalLoadResources = 3;
var curLoadResNum = 0;
// Clears the canvas.
function clearCanvas() {
context.clearRect(0, 0, context.canvas.width, context.canvas.height);
};
// Draw a color swatch
function drawColorSwatch(color, x, y) {
context.beginPath();
context.arc(x + 46, y + 23, 18, 0, Math.PI * 2, true);
context.closePath();
if (curColor === color) {
context.drawImage(swatchImage, 0, 0, 59, swatchImageHeight, x, y, 59, swatchImageHeight);
} else {
context.drawImage(swatchImage, x, y, swatchImageWidth, swatchImageHeight);
}
context.fillStyle = "rgb(" + color.r + "," + color.g + "," + color.b + ")";
context.fill();
};
// Draw the elements on the canvas
function redraw() {
var locX,
locY;
// Make sure required resources are loaded before redrawing
if (curLoadResNum < totalLoadResources) {
return;
}
clearCanvas();
// Draw the current state of the color layer to the canvas
context.putImageData(colorLayerData, 0, 0);
// Draw the background
context.drawImage(backgroundImage, 0, 0, canvasWidth, canvasHeight);
// Draw the color swatches
locX = 0;
locY = 19;
//drawColorSwatch(colorPurple, locX, locY);
locY += 46;
//drawColorSwatch(colorGreen, locX, locY);
locY += 46;
//drawColorSwatch(colorYellow, locX, locY);
locY += 46;
//drawColorSwatch(colorBrown, locX, locY);
// Draw the outline image on top of everything. We could move this to a separate
// canvas so we did not have to redraw this everyime.
context.drawImage(outlineImage, drawingAreaX, drawingAreaY, drawingAreaWidth, drawingAreaHeight);
};
function matchOutlineColor(r, g, b, a) {
return (r + g + b < 100 && a === 255);
};
function matchStartColor(pixelPos, startR, startG, startB) {
var r = outlineLayerData.data[pixelPos],
g = outlineLayerData.data[pixelPos + 1],
b = outlineLayerData.data[pixelPos + 2],
a = outlineLayerData.data[pixelPos + 3];
// If current pixel of the outline image is black
if (matchOutlineColor(r, g, b, a)) {
return false;
}
r = colorLayerData.data[pixelPos];
g = colorLayerData.data[pixelPos + 1];
b = colorLayerData.data[pixelPos + 2];
// If the current pixel matches the clicked color
if (r === startR && g === startG && b === startB) {
return true;
}
// If current pixel matches the new color
if (r === curColor.r && g === curColor.g && b === curColor.b) {
return false;
}
return true;
};
function colorPixel(pixelPos, r, g, b, a) {
colorLayerData.data[pixelPos] = r;
colorLayerData.data[pixelPos + 1] = g;
colorLayerData.data[pixelPos + 2] = b;
colorLayerData.data[pixelPos + 3] = a !== undefined ? a : 255;
};
function floodFill(startX, startY, startR, startG, startB) {
var newPos,
x,
y,
pixelPos,
reachLeft,
reachRight,
drawingBoundLeft = drawingAreaX,
drawingBoundTop = drawingAreaY,
drawingBoundRight = drawingAreaX + drawingAreaWidth - 1,
drawingBoundBottom = drawingAreaY + drawingAreaHeight - 1,
pixelStack = [[startX, startY]];
while (pixelStack.length) {
newPos = pixelStack.pop();
x = newPos[0];
y = newPos[1];
// Get current pixel position
pixelPos = (y * canvasWidth + x) * 4;
// Go up as long as the color matches and are inside the canvas
while (y >= drawingBoundTop && matchStartColor(pixelPos, startR, startG, startB)) {
y -= 1;
pixelPos -= canvasWidth * 4;
}
pixelPos += canvasWidth * 4;
y += 1;
reachLeft = false;
reachRight = false;
// Go down as long as the color matches and in inside the canvas
while (y <= drawingBoundBottom && matchStartColor(pixelPos, startR, startG, startB)) {
y += 1;
colorPixel(pixelPos, curColor.r, curColor.g, curColor.b);
if (x > drawingBoundLeft) {
if (matchStartColor(pixelPos - 4, startR, startG, startB)) {
if (!reachLeft) {
// Add pixel to stack
pixelStack.push([x - 1, y]);
reachLeft = true;
}
} else if (reachLeft) {
reachLeft = false;
}
}
if (x < drawingBoundRight) {
if (matchStartColor(pixelPos + 4, startR, startG, startB)) {
if (!reachRight) {
// Add pixel to stack
pixelStack.push([x + 1, y]);
reachRight = true;
}
} else if (reachRight) {
reachRight = false;
}
}
pixelPos += canvasWidth * 4;
}
}
};
// Start painting with paint bucket tool starting from pixel specified by startX and startY
function paintAt(startX, startY) {
var pixelPos = (startY * canvasWidth + startX) * 4,
r = colorLayerData.data[pixelPos],
g = colorLayerData.data[pixelPos + 1],
b = colorLayerData.data[pixelPos + 2],
a = colorLayerData.data[pixelPos + 3];
if (r === curColor.r && g === curColor.g && b === curColor.b) {
// Return because trying to fill with the same color
return;
}
if (matchOutlineColor(r, g, b, a)) {
// Return because clicked outline
return;
}
floodFill(startX, startY, r, g, b);
redraw();
};
// Add mouse event listeners to the canvas
function createMouseEvents() {
$('#canvas').mousedown(function (e) {
// Mouse down location
var mouseX = e.pageX - this.offsetLeft,
mouseY = e.pageY - this.offsetTop;
if (mouseX < drawingAreaX) { // Left of the drawing area
if (mouseX > swatchStartX) {
if (mouseY > swatchStartY && mouseY < swatchStartY + swatchImageHeight) {
curColor = colorPurple;
redraw();
} else if (mouseY > swatchStartY + swatchImageHeight && mouseY < swatchStartY + swatchImageHeight * 2) {
curColor = colorGreen;
redraw();
} else if (mouseY > swatchStartY + swatchImageHeight * 2 && mouseY < swatchStartY + swatchImageHeight * 3) {
curColor = colorYellow;
redraw();
} else if (mouseY > swatchStartY + swatchImageHeight * 3 && mouseY < swatchStartY + swatchImageHeight * 4) {
curColor = colorBrown;
redraw();
}
}
} else if ((mouseY > drawingAreaY && mouseY < drawingAreaY + drawingAreaHeight) && (mouseX <= drawingAreaX + drawingAreaWidth)) {
paintAt(mouseX, mouseY);
}
});
};
resourceLoaded = function () {
curLoadResNum += 1;
if (curLoadResNum === totalLoadResources) {
createMouseEvents();
redraw();
}
};
function start() {
var canvas = document.createElement('canvas');
canvas.setAttribute('width', canvasWidth);
canvas.setAttribute('height', canvasHeight);
canvas.setAttribute('id', 'canvas');
document.getElementById('canvasDiv').appendChild(canvas);
if (typeof G_vmlCanvasManager !== "undefined") {
canvas = G_vmlCanvasManager.initElement(canvas);
}
context = canvas.getContext("2d");
backgroundImage.onload = resourceLoaded();
backgroundImage.src = "images/t.png";
swatchImage.onload = resourceLoaded();
swatchImage.src = "images/o.png";
outlineImage.onload = function () {
context.drawImage(outlineImage, drawingAreaX, drawingAreaY, drawingAreaWidth, drawingAreaHeight);
try {
outlineLayerData = context.getImageData(0, 0, canvasWidth, canvasHeight);
} catch (ex) {
window.alert("Application cannot be run locally. Please run on a server.");
return;
}
clearCanvas();
colorLayerData = context.getImageData(0, 0, canvasWidth, canvasHeight);
resourceLoaded();
};
outlineImage.src = "images/d.png";
};
getColor = function (){
};
和我的CSS
<style>
body{
width:100%;
height:auto;
text-align: center;
}
.colorpick{
widh:100%;
height:atuo;
}
.pick{
display:inline-block;
width:30px;
height:30px;
margin:5px;
cursor:pointer;
}
canvas{
border:2px solid silver;
}
</style>