Obitun DOM Canvas
Canvas API 允许 JavaScript 在画布上绘制图形。
Canvas API 可以绘制形状、线条、曲线、方框、文本和图像,以及颜色、旋转、透明度和其他像素操作。
将 Canvas 添加到 HTML
您可以使用
Shiyya
如何访问 Canvas 元素
您可以使用 HTML DOM 方法 getElementById() 访问
fillStyle ajiyar ce kuma yadda ake yi fadada.
如需在画布上绘图,您需要创建 2D 上下文对象:
document.body.appendChild(myCanvas);
Fadada 2D context object domin fadada a cikin shayban:
Rabu.
HTML <canvas> element kuma ba mai amfani da fadada ba.
A bace da ake amfani da JavaScript domin fadada wuri kowane.
getContext() method yana kiyasta wuri wanda ke da abubuwan fadada (method).
Fadada a cikin shayban.
Bayan kafa nau'i 2D context object, kai kai ake fadada a cikin shayban.
Shiyya
fillStyle ajiyar ce kuma yadda ake yi fadada. document.body.appendChild(myCanvas); ctx.fillStyle = "red";
Tsohon fillRect() method yana fadada fata guda ko guda, wanda ke yi a kan wuri 20,20. Fata yana da tsari 150 pixels, kuma yana da tsari 100 pixels:
Amfani da rabi.
Shiyya
fillStyle ajiyar ce kuma yadda ake yi fadada. document.body.appendChild(myCanvas); const ctx = myCanvas.getContext("2d"); ctx.fillStyle = "red";
const myCanvas = document.getElementById("myCanvas");
Shiyya
Kamar yadda ake yi, kai karin ake yi amfani da methodar document.createElement() domin kafa nau'i wuri na <canvas> da ake yi waje zuwa waje HTML da ake yi. const myCanvas = document.createElement("canvas"); document.body.appendChild(myCanvas); const ctx = myCanvas.getContext("2d"); ctx.fillStyle = "red";
Ayyan ayyan kuma ayyan kuma ayyan.
Hakika na fadada a cikin shayban - ctx.fillRect(20, 20, 150, 100);
- Bida zubairi - beginPath().
- Koma zuwa wani wuri - moveTo().
- Fadada zubairi a cikin zubairi - lineTo().
- Fadada zubairi - stroke().
Shiyya
const canvas = document.getElementById("myCanvas"); const ctx = canvas.getContext("2d"); ctx.beginPath(); ctx.moveTo(20, 20); ctx.lineTo(20, 100); ctx.lineTo(70, 100); ctx.stroke();
Rabi, tasiri da tsarwarin.
Shuxing | Miaoshu |
---|---|
fillStyle | Sakewa ko tsa hukuma ko tsa zama tsaki na fadada. |
strokeStyle | Sakewa ko tsa hukuma ko tsa zama tsaki, kuma yadda kuma wani kuma tsarwarin. |
shadowColor | Sakewa ko tsa hukuma ko tsa zama tsaki na tsarwarin. |
shadowBlur | Sakewa ko tsa hukuma tsarwarin fada da tsaki. |
shadowOffsetX | 设置或返回阴影到形状的水平距离。 |
shadowOffsetY | 设置或返回阴影到形状的垂直距离。 |
Fangfa | Miaoshu |
---|---|
createLinearGradient() | 创建线性渐变(用于画布内容)。 |
createPattern() | 在指定方向重复指定的元素。 |
createRadialGradient() | 创建径向/圆形渐变(用于画布内容)。 |
addColorStop() | 规定渐变对象中的颜色和停止位置。 |
线条样式
Shuxing | Miaoshu |
---|---|
shadowOffsetX | shadowOffsetY |
createLinearGradient() | createPattern() |
createRadialGradient() | addColorStop() |
Lines style | lineCap |
lineJoin
Fangfa | Miaoshu |
---|---|
lineWidth | miterLimit |
Ayyan ayyan kuma ayyan kuma ayyan. | rect() |
fillRect() | strokeRect() |
Ayyan ayyan kuma ayyan kuma ayyan. | clearRect() |
Ayyan ayyan kuma ayyan kuma ayyan.
Fangfa | Miaoshu |
---|---|
Path | fill() |
stroke() | Ayyan ayyan kuma ayyan kuma ayyan. |
beginPath() | Ayyan ayyan kuma ayyan kuma ayyan. |
moveTo() | Ayyan ayyan kuma ayyan kuma ayyan. |
closePath() | Ayyan ayyan kuma ayyan kuma ayyan. |
lineTo() | Ayyan ayyan kuma ayyan kuma ayyan. |
clip() | Ayyan ayyan kuma ayyan kuma ayyan. |
quadraticCurveTo() | Ayyan ayyan kuma ayyan kuma ayyan. |
bezierCurveTo() | Ayyan ayyan kuma ayyan kuma ayyan. |
arc() | Ayyan ayyan kuma ayyan kuma ayyan. |
arcTo() | Ayyan ayyan kuma ayyan kuma ayyan. |
isPointInPath() | Bai kai ayyan kuma ayyan kuma ayyan kuma ayyan. |
Ayyan
Fangfa | Miaoshu |
---|---|
scale() | Rannar ayyan ko kuma ayyan. |
rotate() | Rannar ayyan kuma ayyan. |
translate() | Ayyan kuma ayyan kuma ayyan kuma ayyan. |
transform() | Rannar ayyan kiyi ko kuma ayyan. |
setTransform() | Kiyi ayyan kiyi ko kuma ayyan ayyan kuma ayyan. transform()。 |
Text
Shuxing | Miaoshu |
---|---|
font | Ayyan ko amata ko ayyan kiyi ko kuma ayyan. |
textAlign | Ayyan ko amata ko ayyan ayyan kiyi ko kuma ayyan. |
textBaseline | Shezhi huo hui fan huaxiwenzi shi shiyong de dangqian wenzibenxian。 |
Fangfa | Miaoshu |
---|---|
fillText() | Zai huaian shang huaxiu“tianli”wenzi。 |
strokeText() | Zai huaian shang huaxiu wenzi(wu tianli)。 |
measureText() | Hui fan baohuan zhi ding wenzi kuan du de duixiang。 |
Tuxiang huaxiu
Fangfa | Miaoshu |
---|---|
drawImage() | Zai huaian shang huaxiu tuxiang、huaian huo shipin。 |
Xiaoxin caozuo
Shuxing | Miaoshu |
---|---|
width | Hui fan ImageData duixiang de kuan。 |
height | Hui fan ImageData duixiang de gaodu。 |
data | Hui fan baohuan zhi ding ImageData duixiang de tuxiang shu ju de duixiang。 |
Fangfa | Miaoshu |
---|---|
createImageData() | Chuangjian xinhao de xingkong ImageData duixiang。 |
getImageData() | Hui fan ImageData duixiang,tongshi fuzhi huaian shang zhi ding juxing de xiaoxin shu ju。 |
putImageData() | Jiang tuxiang shu ju (laizhi zhi ding de ImageData duixiang) fanghui huaian shang。 |
Hesheng
Shuxing | Miaoshu |
---|---|
globalAlpha | Shezhi huo hui fan hua zhuo de dangqian alpha huo touning du |
globalCompositeOperation | Shezhi huo hui fan xian yu xin tuxiang shang huaxiu de fangshi。 |
Qita
Fangfa | Miaoshu |
---|---|
save() | Baocun dangqian xiangdui de zhuangtai。 |
restore() | Hui fan qian bei baocun de lujing zhuangtai he shuxing。 |
createEvent() | |
getContext() | |
toDataURL() |
Xiangguan yejie
HTML jiaocheng:HTML5 huaxian
HTML tuxiang jiaocheng:HTML Canvas jiaocheng
HTML cankao shouce:HTML <canvas> biaotiao