我正在寻找以下问题的解决方案：如何将 a 的大小更改为Bitmap固定大小（例如 512x128）。必须保留位图内容的纵横比。
我认为应该是这样的：
创建一个空的 512x128 位图
在保持纵横比的情况下缩小原始位图以适应 512x128 像素
将缩放后的位图复制到空位图中（居中）
实现这一目标的最简单方法是什么？
这一切的原因是，GridView当图像的纵横比与另一个不同时，布局会变得混乱。这是一个屏幕截图（除最后一张外，所有图像的纵横比均为 4:1）：
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29806 次
5 回答
40
试试这个，计算比率，然后重新调整。
private Bitmap scaleBitmap(Bitmap bm) {
int width = bm.getWidth();
int height = bm.getHeight();
Log.v("Pictures", "Width and height are " + width + "--" + height);
if (width > height) {
// landscape
float ratio = (float) width / maxWidth;
width = maxWidth;
height = (int)(height / ratio);
} else if (height > width) {
// portrait
float ratio = (float) height / maxHeight;
height = maxHeight;
width = (int)(width / ratio);
} else {
// square
height = maxHeight;
width = maxWidth;
}
Log.v("Pictures", "after scaling Width and height are " + width + "--" + height);
bm = Bitmap.createScaledBitmap(bm, width, height, true);
return bm;
}
于 2014-04-05T15:29:31.610 回答
22
Coen Damen 的回答并不总是尊重最大高度和最大宽度。这是一个答案：
private static Bitmap resize(Bitmap image, int maxWidth, int maxHeight) {
if (maxHeight > 0 && maxWidth > 0) {
int width = image.getWidth();
int height = image.getHeight();
float ratioBitmap = (float) width / (float) height;
float ratioMax = (float) maxWidth / (float) maxHeight;
int finalWidth = maxWidth;
int finalHeight = maxHeight;
if (ratioMax > 1) {
finalWidth = (int) ((float)maxHeight * ratioBitmap);
} else {
finalHeight = (int) ((float)maxWidth / ratioBitmap);
}
image = Bitmap.createScaledBitmap(image, finalWidth, finalHeight, true);
return image;
} else {
return image;
}
}
于 2015-02-06T13:32:18.103 回答
2
我在我的项目中多次偶然发现同样的问题，每次由于缺乏时间（和懒惰），我都会对一个不太理想的解决方案感到满意。但最近我找到了一些时间来解决这个特殊问题。这是我的解决方案，我希望它可以帮助某人。
Bitmap scaleDownLargeImageWithAspectRatio(Bitmap image)
{
int imageVerticalAspectRatio,imageHorizontalAspectRatio;
float bestFitScalingFactor=0;
float percesionValue=(float) 0.2;
//getAspect Ratio of Image
int imageHeight=(int) (Math.ceil((double) image.getHeight()/100)*100);
int imageWidth=(int) (Math.ceil((double) image.getWidth()/100)*100);
int GCD=BigInteger.valueOf(imageHeight).gcd(BigInteger.valueOf(imageWidth)).intValue();
imageVerticalAspectRatio=imageHeight/GCD;
imageHorizontalAspectRatio=imageWidth/GCD;
Log.i("scaleDownLargeImageWIthAspectRatio","Image Dimensions(W:H): "+imageWidth+":"+imageHeight);
Log.i("scaleDownLargeImageWIthAspectRatio","Image AspectRatio(W:H): "+imageHorizontalAspectRatio+":"+imageVerticalAspectRatio);
//getContainer Dimensions
int displayWidth = getWindowManager().getDefaultDisplay().getWidth();
int displayHeight = getWindowManager().getDefaultDisplay().getHeight();
//I wanted to show the image to fit the entire device, as a best case. So my ccontainer dimensions were displayWidth & displayHeight. For your case, you will need to fetch container dimensions at run time or you can pass static values to these two parameters
int leftMargin = 0;
int rightMargin = 0;
int topMargin = 0;
int bottomMargin = 0;
int containerWidth = displayWidth - (leftMargin + rightMargin);
int containerHeight = displayHeight - (topMargin + bottomMargin);
Log.i("scaleDownLargeImageWIthAspectRatio","Container dimensions(W:H): "+containerWidth+":"+containerHeight);
//iterate to get bestFitScaleFactor per constraints
while((imageHorizontalAspectRatio*bestFitScalingFactor <= containerWidth) &&
(imageVerticalAspectRatio*bestFitScalingFactor<= containerHeight))
{
bestFitScalingFactor+=percesionValue;
}
//return bestFit bitmap
int bestFitHeight=(int) (imageVerticalAspectRatio*bestFitScalingFactor);
int bestFitWidth=(int) (imageHorizontalAspectRatio*bestFitScalingFactor);
Log.i("scaleDownLargeImageWIthAspectRatio","bestFitScalingFactor: "+bestFitScalingFactor);
Log.i("scaleDownLargeImageWIthAspectRatio","bestFitOutPutDimesions(W:H): "+bestFitWidth+":"+bestFitHeight);
image=Bitmap.createScaledBitmap(image, bestFitWidth,bestFitHeight, true);
//Position the bitmap centre of the container
int leftPadding=(containerWidth-image.getWidth())/2;
int topPadding=(containerHeight-image.getHeight())/2;
Bitmap backDrop=Bitmap.createBitmap(containerWidth, containerHeight, Bitmap.Config.RGB_565);
Canvas can = new Canvas(backDrop);
can.drawBitmap(image, leftPadding, topPadding, null);
return backDrop;
}
于 2014-03-27T06:56:42.240 回答
1
并确保dstWidth和dstHeight都是从src.getWidth()*scale和获得的src.getHeight()*scale，其中scale是您需要确定的值，以确保缩放的位图适合 512x128。
于 2013-02-27T23:02:32.980 回答
1
我认为@Coen 的回答不是这个问题的正确解决方案。我也需要这样的方法，但我想对图像进行平方。
这是我的方形图像解决方案；
public static Bitmap resizeBitmapImageForFitSquare(Bitmap image, int maxResolution) {
if (maxResolution <= 0)
return image;
int width = image.getWidth();
int height = image.getHeight();
float ratio = (width >= height) ? (float)maxResolution/width :(float)maxResolution/height;
int finalWidth = (int) ((float)width * ratio);
int finalHeight = (int) ((float)height * ratio);
image = Bitmap.createScaledBitmap(image, finalWidth, finalHeight, true);
if (image.getWidth() == image.getHeight())
return image;
else {
//fit height and width
int left = 0;
int top = 0;
if(image.getWidth() != maxResolution)
left = (maxResolution - image.getWidth()) / 2;
if(image.getHeight() != maxResolution)
top = (maxResolution - image.getHeight()) / 2;
Bitmap bitmap = Bitmap.createBitmap(maxResolution, maxResolution, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
canvas.drawBitmap(image, left, top, null);
canvas.save();
canvas.restore();
return bitmap;
}
}
于 2018-12-20T09:59:12.303 回答