Einführung in die Verwendung von HTML5-Canvas

Neues Element

Das -Element wird zum Zeichnen von Grafiken verwendet, was über Skripte (normalerweise JavaScript) erfolgt.

Tag ist nur ein Grafikcontainer, Sie müssen ein Skript verwenden, um die Grafiken zu zeichnen.

Mit Canva können Sie auf vielfältige Weise Pfade, Kästchen, Kreise und Zeichen zeichnen und Bilder hinzufügen.

Hinweis: Standardmäßig hat das -Element keine Rahmen oder Inhalte.

　Diagramm

<span style="color: #008000"><!--</span><span style="color: #008000">fillStyle是填充样式，如果不设置fillStyle属性，默认填充色为黑色，fillRect是画一个矩形，参数为X,Y,Width,Height</span><span style="color: #008000">--></span><span style="color: #0000ff"><!</span><span style="color: #ff00ff">DOCTYPE html</span><span style="color: #0000ff">></span><span style="color: #0000ff"><</span><span style="color: #800000">html</span><span style="color: #0000ff">></span><span style="color: #0000ff"><</span><span style="color: #800000">head</span><span style="color: #0000ff">></span><span style="color: #0000ff"><</span><span style="color: #800000">meta </span><span style="color: #ff0000">charset</span><span style="color: #0000ff">="UTF-8"</span><span style="color: #ff0000"> name</span><span style="color: #0000ff">="author"</span><span style="color: #ff0000"> content</span><span style="color: #0000ff">="赵慧娟"</span><span style="color: #0000ff">></span><span style="color: #0000ff"><</span><span style="color: #800000">title</span><span style="color: #0000ff">></</span><span style="color: #800000">title</span><span style="color: #0000ff">></span><span style="color: #0000ff"><</span><span style="color: #800000">script </span><span style="color: #ff0000">src</span><span style="color: #0000ff">="Scripts/jquery-1.10.2.js?1.1.10"</span><span style="color: #0000ff">></</span><span style="color: #800000">script</span><span style="color: #0000ff">></span><span style="color: #0000ff"><</span><span style="color: #800000">script </span><span style="color: #ff0000">type</span><span style="color: #0000ff">="text/javascript"</span><span style="color: #0000ff">></span><span style="background-color: #f5f5f5; color: #000000">$(</span><span style="background-color: #f5f5f5; color: #0000ff">function</span><span style="background-color: #f5f5f5; color: #000000">(){</span><span style="background-color: #f5f5f5; color: #0000ff">var</span><span style="background-color: #f5f5f5; color: #000000"> canvas</span><span style="background-color: #f5f5f5; color: #000000">=</span><span style="background-color: #f5f5f5; color: #000000">document.getElementById(</span><span style="background-color: #f5f5f5; color: #000000">"</span><span style="background-color: #f5f5f5; color: #000000">myCanvas</span><span style="background-color: #f5f5f5; color: #000000">"</span><span style="background-color: #f5f5f5; color: #000000">)</span><span style="background-color: #f5f5f5; color: #0000ff">var</span><span style="background-color: #f5f5f5; color: #000000"> ctx</span><span style="background-color: #f5f5f5; color: #000000">=</span><span style="background-color: #f5f5f5; color: #000000">canvas.getContext(</span><span style="background-color: #f5f5f5; color: #000000">"</span><span style="background-color: #f5f5f5; color: #000000">2d</span><span style="background-color: #f5f5f5; color: #000000">"</span><span style="background-color: #f5f5f5; color: #000000">);
                ctx.fillStyle</span><span style="background-color: #f5f5f5; color: #000000">=</span><span style="background-color: #f5f5f5; color: #000000">"</span><span style="background-color: #f5f5f5; color: #000000">deeppink</span><span style="background-color: #f5f5f5; color: #000000">"</span><span style="background-color: #f5f5f5; color: #000000">;
                ctx.fillRect(</span><span style="background-color: #f5f5f5; color: #000000">10</span><span style="background-color: #f5f5f5; color: #000000">,</span><span style="background-color: #f5f5f5; color: #000000">10</span><span style="background-color: #f5f5f5; color: #000000">,</span><span style="background-color: #f5f5f5; color: #000000">100</span><span style="background-color: #f5f5f5; color: #000000">,</span><span style="background-color: #f5f5f5; color: #000000">100</span><span style="background-color: #f5f5f5; color: #000000">);<br>　　　　　　　　 <span style="color: #339966"> //ctx.moveTo(0,0);　　　　//定义开始坐标</span><br><span style="color: #339966">　　　　　　　　　//ctx.lineTo(100,100);　　//定义结束坐标</span><br><span style="color: #339966">　　　　　　　　　//ctx.stroke();　　　　　　//绘制线条</span><br></span>

            })</script></head><body><canvas id="myCanvas" width="100" height="100"></canvas></body></html>

Laufergebnis:

Zeichne einen Kreis

<span style="color: #008000"><!--</span><span style="color: #008000">arc画圆，参数是X,Y,半径，起始角，结束角，顺时针/逆时针(可选)XY指的是圆点的距离</span><span style="color: #008000">--></span><span style="color: #0000ff"><!</span><span style="color: #ff00ff">DOCTYPE html</span><span style="color: #0000ff">></span><span style="color: #0000ff"><</span><span style="color: #800000">html</span><span style="color: #0000ff">></span><span style="color: #0000ff"><</span><span style="color: #800000">head</span><span style="color: #0000ff">></span><span style="color: #0000ff"><</span><span style="color: #800000">meta </span><span style="color: #ff0000">charset</span><span style="color: #0000ff">="UTF-8"</span><span style="color: #ff0000"> name</span><span style="color: #0000ff">="author"</span><span style="color: #ff0000"> content</span><span style="color: #0000ff">="赵慧娟"</span><span style="color: #0000ff">></span><span style="color: #0000ff"><</span><span style="color: #800000">title</span><span style="color: #0000ff">></</span><span style="color: #800000">title</span><span style="color: #0000ff">></span><span style="color: #0000ff"><</span><span style="color: #800000">script </span><span style="color: #ff0000">src</span><span style="color: #0000ff">="Scripts/jquery-1.10.2.js?1.1.10"</span><span style="color: #0000ff">></</span><span style="color: #800000">script</span><span style="color: #0000ff">></span><span style="color: #0000ff"><</span><span style="color: #800000">script </span><span style="color: #ff0000">type</span><span style="color: #0000ff">="text/javascript"</span><span style="color: #0000ff">></span><span style="background-color: #f5f5f5; color: #000000">$(</span><span style="background-color: #f5f5f5; color: #0000ff">function</span><span style="background-color: #f5f5f5; color: #000000">(){</span><span style="background-color: #f5f5f5; color: #0000ff">var</span><span style="background-color: #f5f5f5; color: #000000"> canvas</span><span style="background-color: #f5f5f5; color: #000000">=</span><span style="background-color: #f5f5f5; color: #000000">document.getElementById(</span><span style="background-color: #f5f5f5; color: #000000">"</span><span style="background-color: #f5f5f5; color: #000000">myCanvas</span><span style="background-color: #f5f5f5; color: #000000">"</span><span style="background-color: #f5f5f5; color: #000000">)</span><span style="background-color: #f5f5f5; color: #0000ff">var</span><span style="background-color: #f5f5f5; color: #000000"> ctx</span><span style="background-color: #f5f5f5; color: #000000">=</span><span style="background-color: #f5f5f5; color: #000000">canvas.getContext(</span><span style="background-color: #f5f5f5; color: #000000">"</span><span style="background-color: #f5f5f5; color: #000000">2d</span><span style="background-color: #f5f5f5; color: #000000">"</span><span style="background-color: #f5f5f5; color: #000000">);
                ctx.fillStyle</span><span style="background-color: #f5f5f5; color: #000000">=</span><span style="background-color: #f5f5f5; color: #000000">"</span><span style="background-color: #f5f5f5; color: #000000">deeppink</span><span style="background-color: #f5f5f5; color: #000000">"</span><span style="background-color: #f5f5f5; color: #000000">;
                ctx.arc(</span><span style="background-color: #f5f5f5; color: #000000">50</span><span style="background-color: #f5f5f5; color: #000000">,</span><span style="background-color: #f5f5f5; color: #000000">50</span><span style="background-color: #f5f5f5; color: #000000">,</span><span style="background-color: #f5f5f5; color: #000000">50</span><span style="background-color: #f5f5f5; color: #000000">,</span><span style="background-color: #f5f5f5; color: #000000">0</span><span style="background-color: #f5f5f5; color: #000000">,</span><span style="background-color: #f5f5f5; color: #000000">2</span><span style="background-color: #f5f5f5; color: #000000">*</span><span style="background-color: #f5f5f5; color: #000000">Math.PI);
                ctx.stroke();<br><span class="hl-identifier">　　　　　　　　　<span style="color: #339966">//ctx</span><span class="hl-code"><span style="color: #339966">.</span><span class="hl-identifier"><span style="color: #339966">fillText</span><span class="hl-brackets"><span style="color: #339966">(</span><span class="hl-quotes"><span style="color: #339966">"</span><span class="hl-string"><span style="color: #339966">Hello World</span><span class="hl-quotes"><span style="color: #339966">"</span><span class="hl-code"><span style="color: #339966">,</span><span class="hl-number"><span style="color: #339966">10</span><span class="hl-code"><span style="color: #339966">,</span><span class="hl-number"><span style="color: #339966">50</span><span class="hl-brackets"><span style="color: #339966">)</span><span class="hl-code"><span style="color: #339966">;　　//绘制实心字体</span><br><span style="color: #339966">　　　　　　　　　//<span class="hl-identifier">ctx<span class="hl-code">.<span class="hl-identifier">strokeText<span class="hl-brackets">(<span class="hl-quotes">"<span class="hl-string">Hello World<span class="hl-quotes">"<span class="hl-code">,<span class="hl-number">10<span class="hl-code">,<span class="hl-number">50<span class="hl-brackets">)<span class="hl-code">;　//绘制空心字体</span></span></span></span></span></span></span></span></span></span></span></span></span></span><br></span></span></span></span></span></span></span></span></span></span></span></span></span>})</span><span style="color: #0000ff"></</span><span style="color: #800000">script</span><span style="color: #0000ff">></span><span style="color: #0000ff"><</span><span style="color: #800000">style </span><span style="color: #ff0000">type</span><span style="color: #0000ff">="text/css"</span><span style="color: #0000ff">></span><span style="background-color: #f5f5f5; color: #800000">canvas</span><span style="background-color: #f5f5f5; color: #000000">{</span><span style="background-color: #f5f5f5; color: #ff0000">border</span><span style="background-color: #f5f5f5; color: #000000">:</span><span style="background-color: #f5f5f5; color: #0000ff"> 1px solid #000</span><span style="background-color: #f5f5f5; color: #000000">;</span><span style="background-color: #f5f5f5; color: #000000">}</span><span style="color: #0000ff"></</span><span style="color: #800000">style</span><span style="color: #0000ff">></span><span style="color: #0000ff"></</span><span style="color: #800000">head</span><span style="color: #0000ff">></span><span style="color: #0000ff"><</span><span style="color: #800000">body</span><span style="color: #0000ff">></span><span style="color: #0000ff"><</span><span style="color: #800000">canvas </span><span style="color: #ff0000">id</span><span style="color: #0000ff">="myCanvas"</span><span style="color: #ff0000"> width</span><span style="color: #0000ff">="100"</span><span style="color: #ff0000"> height</span><span style="color: #0000ff">="100"</span><span style="color: #0000ff">></</span><span style="color: #800000">canvas</span><span style="color: #0000ff">></span><span style="color: #0000ff"></</span><span style="color: #800000">body</span><span style="color: #0000ff">></span><span style="color: #0000ff"></</span><span style="color: #800000">html</span><span style="color: #0000ff">></span>

Laufergebnis:

　Verlauf

CreateLinearGradient(x,y,x1,y1) – Erstellen Sie einen Linienverlauf

createRadialGradient(x,y,r,x1,y1,r1 ) – Erstellen Sie einen radialen/kreisförmigen Farbverlauf

// 创建渐变var grd=ctx.createLinearGradient(0,0,200,0);
grd.addColorStop(0,"red");
grd.addColorStop(1,"blue"); 
// 填充渐变ctx.fillStyle=grd;
ctx.fillRect(10,10,150,80);

Laufergebnis:

　Radialer/kreisförmiger Farbverlauf

var c=document.getElementById("myCanvas");
var ctx=c.getContext("2d");
 
// 创建渐变
var grd=ctx.createRadialGradient(75,50,5,90,60,100);
grd.addColorStop(0,"red");
grd.addColorStop(1,"white");
 
// 填充渐变
ctx.fillStyle=grd;
ctx.fillRect(10,10,150,80);

Laufergebnis:

Bild

<!DOCTYPE html><html><head><meta charset="UTF-8" name="author" content="赵慧娟"><title></title><script src="Scripts/jquery-1.10.2.js?1.1.10"></script><style type="text/css">canvas{border: 1px solid #000;}#flower{border: 1px solid #000;width: 100px;height: 100px;}</style></head><body><img src="img/a.ico" id="flower" /><canvas id="myCanvas" width="100" height="100"></canvas><script type="text/javascript">$(function(){var canvas=document.getElementById("myCanvas")var ctx=canvas.getContext("2d");var img=document.getElementById("flower");
                img.onload=function(){
                    ctx.drawImage(img,20,20,80,80);　　//drawImage（对象，X,Y，W,H）}
            })</script></body></html>

Laufergebnis:

(Das Bild rechts ist das Leinwandbild)

Das obige ist der detaillierte Inhalt vonEinführung in die Verwendung von HTML5-Canvas. Für weitere Informationen folgen Sie bitte anderen verwandten Artikeln auf der PHP chinesischen Website!