我使用 drawImage 將 1x2 像素精靈拉伸為 300x2 水平線。這曾經(jīng)工作得很好，但最近我注意到 Chrome、Firefox 和 Edge 上有一個問題，drawImage 函數(shù)將開始包含 1x2 定義框之外的精靈數(shù)據(jù)。（順便說一句，這不會發(fā)生在移動設(shè)備上）在下面的鏈接中，繪制線條對于小長度來說效果很好，但是一旦長度超過 255 像素，它將開始繪制不需要的顏色（藍色）。JSFiddle；https://jsfiddle.net/y6bo1zfu/1/任何人都知道這可能是什么原因造成的？這可能是一個已知的錯誤還是通過優(yōu)化添加的意外功能？嘗試將圖像拉伸為其默認寬度 256 倍是禁忌嗎？
1 回答
慕蓋茨4494581
TA貢獻1850條經(jīng)驗 獲得超11個贊
這是由硬件加速 (HWA)（即 GPU）引起的。您可以在自己的瀏覽器上禁用它，您會看到它會按預(yù)期工作。
遺憾的是，您無法要求所有用戶禁用 HWA。
解決這個問題的一種簡單方法是創(chuàng)建一個僅包含圖像所需部分的 ImageBitmap。
這非常簡單，因為該createImageBitmap()方法接受 5 個參數(shù)版本
createImageBitmap( source, sourceX, sourceY, sourceWidth, sourceHeight );
并且drawImage()接受 5 參數(shù)版本
drawImage( source, destinationX, destinationY, destinationWidth, destinationHeight );
因此，您可以將 9 個參數(shù)版本重寫drawImage()為
drawImage(
await createImageBitmap( source, sourceX, sourceY, sourceWidth, sourceHeight ),
destinationX, destinationY, destinationWidth, destinationHeight
)
var rawImage = false;
var testCanvas = document.createElement('canvas');
testCanvas.width = 300;
testCanvas.height = 20;
var testContext = testCanvas.getContext("2d");
testContext.imageSmoothingEnabled = false;
document.body.appendChild( testCanvas );
function loadImage()
{
rawImage = new Image();
rawImage.onload = function(){
// Create the sprite image
createSpriteImage();
document.body.appendChild( rawImage );
}
rawImage.src = "data:image/png;base64,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";
}
async function createSpriteImage()
{
testContext.drawImage(
await createImageBitmap(rawImage,
2, // Source X for this part of the Sprite
1 , // Source Y for this part of the Sprite
1 , // Width of this part of the Sprite
2 // Height of this part of the Sprite
),
0, // The X position where to draw
0, // The Y position where to draw
300 , // Width of the line
2 // Height of the line
);
testContext.drawImage(
await createImageBitmap(rawImage,
2, // Source X for this part of the Sprite
1 , // Source Y for this part of the Sprite
1 , // Width of this part of the Sprite
2 // Height of this part of the Sprite
) ,
0 , // The X position where to draw
3 , // The Y position where to draw
298 , // Width of the line
2 // Height of the line
);
testContext.drawImage(
await createImageBitmap(rawImage,
2, // Source X for this part of the Sprite
1 , // Source Y for this part of the Sprite
1 , // Width of this part of the Sprite
2 // Height of this part of the Sprite
) ,
0, // The X position where to draw
6, // The Y position where to draw
264 , // Width of the line
2 // Height of the line
);
testContext.drawImage(
await createImageBitmap(rawImage,
2, // Source X for this part of the Sprite
1 , // Source Y for this part of the Sprite
1 , // Width of this part of the Sprite
2 // Height of this part of the Sprite
),
0, // The X position where to draw
9, // The Y position where to draw
256 , // Width of the line
2 // Height of the line
);
testContext.drawImage(
await createImageBitmap(rawImage,
2, // Source X for this part of the Sprite
1 , // Source Y for this part of the Sprite
1 , // Width of this part of the Sprite
2 // Height of this part of the Sprite
),
0, // The X position where to draw
12, // The Y position where to draw
255 , // Width of the line
2 , // Height of the line
);
testContext.drawImage(
await createImageBitmap(rawImage,
2, // Source X for this part of the Sprite
1 , // Source Y for this part of the Sprite
1 , // Width of this part of the Sprite
2 // Height of this part of the Sprite
),
0, // The X position where to draw
15, // The Y position where to draw
100 , // Width of the line
2 , // Height of the line
);
testContext.drawImage(
await createImageBitmap(rawImage,
2, // Source X for this part of the Sprite
1 , // Source Y for this part of the Sprite
1 , // Width of this part of the Sprite
2 // Height of this part of the Sprite
),
0, // The X position where to draw
18, // The Y position where to draw
10 , // Width of the line
2 , // Height of the line
);
}
//
loadImage();
body,html {
margin: 0px;
background-color: #4f4f4f;
}
img
{
display: block;
width: 50px;
height: 50px;
margin: 0px auto;
image-rendering: pixelated;
}
canvas
{
display: block;
width: 300px;
height: 20px;
box-shadow: 1px 1px 4px black;
margin: 15px auto;
background-color: white;
border: 1px solid white;
}
而對于不支持 ImageBitmap 接口的瀏覽器，至少可以通過使用其他畫布來對這種用法進行猴子修補。
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