html5 Canvasの基本機能をサンプルコードで共有-H5 チュートリアル-php.cn

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html5 Canvasの基本機能をサンプルコードで共有

黄舟

Mar 28, 2017 pm 03:53 PM

html5 Canvas 基本的な

プロパティ

とcanvasのメソッドの紹介: width、height 、getContext() など;

width

および height を通じて現在のキャンバスの幅と高さを取得および設定します。 getContext() を通じて現在のキャンバスの描画環境 (コンテキスト) を取得します。 メソッド;

context= Canvas.getContext("2d");contextには、キャンバス上に描画する必要があるすべてのメソッドと属性が含まれています。原点から右へはの正の方向です

現在の状態は実際には描画状態のスタックであり、グローバルからキャンバス全体に適用されます。スコープ;

次の状態を操作できます:

変換行列 (変換行列)

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8" />
        <title>s3</title>
        <script type="text/javascript" src="../script/modernizr-latest.js"></script>
        <script type="text/javascript">
            window.addEventListener("load", eventWindowLoaded, false);
            var Debugger = function() {
            };
            Debugger.log = function(message) {
                try {
                    console.log(message);
                } catch (exception) {
                    return;
                }
            }
            function eventWindowLoaded() {
                canvasApp();
            }
 
            function canvasSupport() {
                return Modernizr.canvas;
            }
 
            function eventWindowLoaded() {
                canvasApp();
            }
 
            function canvasApp() {
 
                if(!canvasSupport()) {
                    return;
                }
                var theCanvas = document.getElementById("canvasOne");
                var context = theCanvas.getContext("2d");
 
                function drawScreen() {
                    //以下代码来源于<http://www.cnblogs.com/nothingbrother/archive/2011/12/23/2299856.html>
for(var x = 0.5; x < 550; x += 10) {
                        context.moveTo(x, 0);
                        context.lineTo(x, 400);
                    }
                    for(var y = 0.5; y < 400; y += 10) {
                        context.moveTo(0, y);
                        context.lineTo(550, y);
                    }
                    context.strokeStyle = "#cecece";
                    context.stroke();
                    context.beginPath();
                    context.moveTo(50, 150);
                    context.lineTo(300, 150);
                    context.moveTo(250, 100);
                    context.lineTo(300, 150);
                    context.moveTo(300, 50);
                    context.lineTo(250, 100);
                    context.moveTo(450, 200);
                    context.lineTo(300, 50);
                    /*symmetry*/
                    context.moveTo(50, 250);
                    context.lineTo(300, 250);
                    context.moveTo(250, 300);
                    context.lineTo(300, 250);
                    context.moveTo(300, 350);
                    context.lineTo(250, 300);
                    context.moveTo(450, 200);
                    context.lineTo(300, 350);
                    /*end*/
                    context.moveTo(50, 150);
                    context.lineTo(50, 250);
                    /*write coordinate*/
                    context.font = "bold 12px sans-serif";
                    context.fillText("( 0 , 0 )", 8, 5);
                    context.fillText("(50, 150)", 58, 155);
                    context.fillText("(300, 150)", 308, 155);
                    context.fillText("(250, 100)", 258, 105);
                    context.fillText("(300, 150)", 308, 155);
                    context.fillText("(300, 50)", 308, 55);
                    context.fillText("(50, 250)", 58, 255);
                    context.fillText("(300, 250)", 308, 255);
                    context.fillText("(250, 350)", 258, 355);
                    context.fillText("(450, 200)", 458, 205);
                    context.strokeStyle = "#f00";
                    context.stroke();
 
                }
                drawScreen();
            }
        </script>
    </head>
    <body>
        <div style="position: absolute; top: 50px; left: 50px;">
            <canvas id="canvasOne" width="550" height="400">
                Your browser does not support HTML5 Canvas.
            </canvas>
        </div>
    </body>
</html>