如何在缩放图像/对象后在画布中拖动它们
How to drag images / objects within Canvas after zooming / scaling them?
下面是我的完整代码。哪个是根据此链接编辑的？如何在画布中拖动图像/对象？。
要求：
基本上，我正在做的是，首先，在canvg的帮助下，用drawSvg在画布上绘制SVG文件。
在这个文件上，我通过markers.js.中的JSON绘制图像（green1.png和orange1.png）
场景1:
如果我在不缩放的情况下平移，那么就可以拖动这些图像（绿色1.png、橙色1.png），并且可以正确地平移画布。
但如果我在平移后缩放，那么由于平移X和平移Y点的原因，图像不会在正确的位置平移。但panX和panY是我们想要平移的点。
场景2:：
如果我先缩放，然后平移，则图像（橙色.png，绿色1.png）正在更改其位置，无法拖动图像（橙色1.png，绿色1.png）。
在这些情况下可以做些什么
HTML代码：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
<head>
<script src="http://code.jquery.com/jquery-1.10.1.min.js"></script>
<style>
canvas {
border:1px solid #000
}
.tooltip{
*position:fixed;
position:absolute;
*background:#ff7;
background:green;
border:1px solid #000;
padding:7px;
font-family:sans-serif;
font-size:12px;
}
.tooltip2 {
*position:fixed;
position:absolute;
background:pink;
border:1px solid #000;
padding:7px;
font-family:sans-serif;
font-size:12px;
}
</style>
</head>
<body>
<script src="http://canvg.googlecode.com/svn/trunk/rgbcolor.js"></script>
<script src="http://canvg.googlecode.com/svn/trunk/StackBlur.js"></script>
<script src="http://canvg.googlecode.com/svn/trunk/canvg.js"></script>
<canvas id="myCanvas" width="800" height="700" style="border: 1px solid;margin-top: 10px;"></canvas>
<div id="buttonWrapper">
<input type="button" id="plus" value="+">
<input type="button" id="minus" value="-">
<input type="button" id="original_size" value="100%">
</div>
<script src="/static/js/markers.js"></script>
<script src="/static/js/draw.js"></script>
</body>
</html>
draw.js:
var dataJSON = data || [];
var dataJSON2 = data2 || [];
window.onload = function(){
//$(function(){
var canvas=document.getElementById("myCanvas");
var ctx=canvas.getContext("2d");
var canvasOffset=$("#myCanvas").offset();
var offsetX=canvasOffset.left;
var offsetY=canvasOffset.top;
var lastX=0;
var lastY=0;
var panX=0;
var panY=0;
var dragging=[];
var dragging2=[];
var isDown=false;
function loadImages(sources, callback){
var images = {};
var loadImages = 0;
var numImages = 0;
//get num of sources
for(var i in sources){
numImages++;
}
for(var i in sources){
images[i] = new Image();
images[i].onload = function(){
if(++loadImages >= numImages){
callback(images);
}
};
images[i].src = sources[i];
}
}
var sources = {orange : '/static/images/orange1.png', green : '/static/images/green1.png'};
// load the tiger image
var svgfiles = ["/static/images/awesome_tiger.svg"];
/*var tiger=new Image();
tiger.onload=function(){
draw();
}
tiger.src="tiger.png";*/
function draw(scaleValue){
ctx.clearRect(0,0,canvas.width,canvas.height);
ctx.save();
ctx.drawSvg(svgfiles[0],panX,panY,400*scaleValue, 400*scaleValue);
//ctx.drawImage(tiger,panX,panY,tiger.width,tiger.height);
//ctx.scale(scaleValue, scaleValue);
loadImages(sources, function(images){
ctx.scale(scaleValue, scaleValue);
for(var i = 0, pos; pos = dataJSON[i]; i++) {
ctx.drawImage(images.orange, parseInt(parseInt(pos.x) + parseInt(panX)), parseInt(parseInt(pos.y) + parseInt(panY)), 20/scaleValue, 20/scaleValue);
}
for(var i = 0, pos; pos = dataJSON2[i]; i++) {
ctx.drawImage(images.green, parseInt(parseInt(pos.x) + parseInt(panX)), parseInt(parseInt(pos.y) + parseInt(panY)), 20/scaleValue, 20/scaleValue);
}
ctx.restore();
});
};
var scaleValue = 1;
var scaleMultiplier = 0.8;
draw(scaleValue);
var startDragOffset = {};
var mouseDown = false;
// add button event listeners
document.getElementById("plus").addEventListener("click", function(){
scaleValue /= scaleMultiplier;
//checkboxZoomPan();
draw(scaleValue);
}, false);
document.getElementById("minus").addEventListener("click", function(){
scaleValue *= scaleMultiplier;
//checkboxZoomPan();
draw(scaleValue);
}, false);
document.getElementById("original_size").addEventListener("click", function(){
scaleValue = 1;
//checkboxZoomPan();
draw(scaleValue);
}, false);
// create an array of any "hit" colored-images
function imagesHitTests(x,y){
// adjust for panning
x-=panX;
y-=panY;
// create var to hold any hits
var hits=[];
// hit-test each image
// add hits to hits[]
loadImages(sources, function(images){
for(var i = 0, pos; pos = dataJSON[i]; i++) {
if(x >= parseInt(pos.x * scaleValue) && x <= parseInt((pos.x * scaleValue) + 20) && y >= parseInt(pos.y * scaleValue) && y <= parseInt((pos.y * scaleValue) + 20)){
hits.push(i);
}
}
});
return(hits);
}
function imagesHitTests2(x,y){
// adjust for panning
//x-=panX;
//x = parseInt(x) - parseInt(panX);
// y-=panY;
x-=panX;
y-=panY;
// create var to hold any hits
var hits2=[];
// hit-test each image
// add hits to hits[]
loadImages(sources, function(images){
for(var i = 0, pos; pos = dataJSON2[i]; i++) {
//if(x > pos.x && x < parseInt(parseInt(pos.x) + parseInt(20)) && y > pos.y && y < parseInt(parseInt(pos.y) + parseInt(20))){
if(x >= parseInt(pos.x * scaleValue) && x <= parseInt((pos.x * scaleValue) + 20) && y >= parseInt(pos.y * scaleValue) && y <= parseInt((pos.y * scaleValue) + 20)){
hits2.push(i);
}
}
});
return(hits2);
}
function handleMouseDown(e){
// get mouse coordinates
mouseX=parseInt(e.clientX-offsetX);
mouseY=parseInt(e.clientY-offsetY);
// set the starting drag position
lastX=mouseX;
lastY=mouseY;
// test if we're over any of the images
dragging=imagesHitTests(mouseX,mouseY);
dragging2=imagesHitTests2(mouseX,mouseY);
// set the dragging flag
isDown=true;
}
function handleMouseUp(e){
// clear the dragging flag
isDown=false;
}
function handleMouseMove(e){
// if we're not dragging, exit
if(!isDown){
return;
}
//get mouse coordinates
mouseX=parseInt(e.clientX-offsetX);
mouseY=parseInt(e.clientY-offsetY);
// calc how much the mouse has moved since we were last here
var dx=mouseX-lastX;
var dy=mouseY-lastY;
// set the lastXY for next time we're here
lastX=mouseX;
lastY=mouseY;
// handle drags/pans
if(dragging.length>0){
// we're dragging images
// move all affected images by how much the mouse has moved
for(var i = 0, pos; pos = dataJSON[dragging[i]]; i++) {
pos.x = parseInt(pos.x) + parseInt(dx);
pos.y = parseInt(pos.y) + parseInt(dy);
}
}
else if(dragging2.length>0){
for(var i = 0, pos1; pos1 = dataJSON2[dragging2[i]]; i++) {
pos1.x = parseInt(pos1.x) + parseInt(dx);
pos1.y = parseInt(pos1.y) + parseInt(dy);
}
}
else{
// we're panning the tiger
// set the panXY by how much the mouse has moved
panX+=dx;
panY+=dy;
}
draw(scaleValue);
}
// use jQuery to handle mouse events
$("#myCanvas").mousedown(function(e){handleMouseDown(e);});
$("#myCanvas").mousemove(function(e){handleMouseMove(e);});
$("#myCanvas").mouseup(function(e){handleMouseUp(e);});
// }); // end $(function(){});
}
markers.js:
data = [
{ "id" :["first"],
"x": ["195"],
"y": ["150"],
"tooltiptxt": ["Region 1"]
},
{
"id" :["second"],
"x": ["255"],
"y": ["180"],
"tooltiptxt": ["Region 2"]
},
{
"id" :["third"],
"x": ["200"],
"y": ["240"],
"tooltiptxt": ["Region 3"]
}
];
data2 = [
{ "id" :["first2"],
"x": ["225"],
"y": ["150"],
"tooltiptxt": ["Region 21"]
},
{
"id" :["second2"],
"x": ["275"],
"y": ["180"],
"tooltiptxt": ["Region 22"]
},
{
"id" :["third3"],
"x": ["300"],
"y": ["240"],
"tooltiptxt": ["Region 23"]
}
];
1.）positionX*xScale和positionY*yScale
2.）在绘图功能中尝试此代码
ctx.drawImage(images.orange, parseInt(parseInt(pos.x) + parseInt(panX / scaleValue)), parseInt(parseInt(pos.y) + parseInt(panY / scaleValue)), 20/scaleValue, 20/scaleValue);
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