帆布吸管

Canvas eyeDropper

本文关键字：帆布      更新时间：2023-09-26

我需要实现一个滴管工具。我希望你点击滴管按钮使其激活，然后使用onmove它会改变我的选色器的颜色当你点击使用onclick它会设置颜色为选色器使用

$('#colorpickerHolder').ColorPickerSetColor(eyeDropperColour);

变量eyedroppercolor将根据你所过的颜色像素使用onclick设置。我想知道我是否必须根据我所拥有的图层来做:canvas和canvasCursor。

我一直在看这个指南，但我不能让它为我的项目工作?http://palebluepixel.org/2011/11/16/html5-canvas-eyedropper/

以下是我的项目:http://www.taffatech.com/Paint.html 我

: 

var eyeDropperActive = false;
var eyeDropperColour;

: 

$("#brushEyeDropper").click(function() {
    if ( eyeDropperActive == true)
    {
      eyeDropperActive = false;
    }
    else if ( eyeDropperActive == false)
    {
     eyeDropperActive = true;
    }
});

创建画布"滴管"工具

这是如何读取画布上任意X/Y的像素颜色:

    function getPixelColor(x, y) {
        var pxData = ctx.getImageData(x,y,1,1);
        return("rgb("+pxData.data[0]+","+pxData.data[1]+","+pxData.data[2]+")");
    }

剩下的就是通过点击画布来控制何时接受颜色

    var eyedropperIsActive=false; 
    // Activate reading pixel colors when a #startDropper button is clicked
    $("#startDropper").click(function(e){eyedropperIsActive=true;});
    // if the tool is active, report the color under the mouse
    $("#canvas").mousemove(function(e){handleMouseMove(e);});
    // when the user clicks on the canvas, turn off the tool 
    // (the last color will remain selected)
    $("#canvas").click(function(e){eyedropperIsActive=false;});

这里是鼠标移动事件处理程序它调用getPixelColor并报告颜色

    // if the tool is active, report any color under the mouse
    function handleMouseMove(e){
      if(!eyedropperIsActive){return;}
      mouseX=parseInt(e.clientX-offsetX);
      mouseY=parseInt(e.clientY-offsetY);
      // Put your mousemove stuff here
      var eyedropColor=getPixelColor(mouseX,mouseY);
      $("#results").css("backgroundColor",getPixelColor(mouseX,mouseY));
    }

下面是代码和提示:http://jsfiddle.net/m1erickson/zpfdv/

<!doctype html>
<html>
<head>
<link rel="stylesheet" type="text/css" media="all" href="css/reset.css" /> <!-- reset css -->
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<style>
    body{ background-color: ivory; padding:30px; }
    canvas{border:1px solid red;}
    #results{width:30px; height:30px; border:1px solid blue;}
</style>
<script>
$(function(){
    var canvas=document.getElementById("canvas");
    var ctx=canvas.getContext("2d");
    var canvasOffset=$("#canvas").offset();
    var offsetX=canvasOffset.left;
    var offsetY=canvasOffset.top;
    var eyedropperIsActive=false;
    drawTestColors(20,20,"red");
    drawTestColors(100,20,"green");
    drawTestColors(180,20,"blue");
    function drawTestColors(x,y,color){
        ctx.beginPath();
        ctx.fillStyle=color;
        ctx.rect(x,y,50,50);
        ctx.fill();
    }

    function getPixelColor(x, y) {
        var pxData = ctx.getImageData(x,y,1,1);
        return("rgb("+pxData.data[0]+","+pxData.data[1]+","+pxData.data[2]+")");
    }

    function handleMouseMove(e){
      if(!eyedropperIsActive){return;}
      mouseX=parseInt(e.clientX-offsetX);
      mouseY=parseInt(e.clientY-offsetY);
      // Put your mousemove stuff here
      var eyedropColor=getPixelColor(mouseX,mouseY);
      $("#results").css("backgroundColor",getPixelColor(mouseX,mouseY));
    }
    $("#canvas").click(function(e){eyedropperIsActive=false;});
    $("#canvas").mousemove(function(e){handleMouseMove(e);});
    $("#startDropper").click(function(e){eyedropperIsActive=true;});
}); // end $(function(){});
</script>
</head>
<body>
    <p>Click "Activate Eyedropper" to read pixel color under the mouse</p>
    <p>Click canvas to set the color and de-active the eyedropper</p>
    <canvas id="canvas" width=300 height=300></canvas><br>
    <button id="startDropper">Activate Eyedropper</button>
    <div id="results" width=30 height=30>&nbsp;</div>
</body>
</html>
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