根据最大和最小宽高限制生成缩略图
在开发聊天APP时，咱们发送图片通常都需要进行压缩。这段代码帮助你生成适合大小的缩略图。1. 对于极长或者极宽的图片进行缩放居中并裁剪。
2. 对于比例合适的图片则进行相应的缩放，使它满足最大和最小宽高限制。
代码:public class BitmapUtils {
/**
* 将原图缩放至合适的比例，比例异常将进行裁剪
* @param source 原图
* @param max 图片最大值
* @param min 图片最小值
* @return 缩放后的图片
*/
public static Bitmap getScaleBitmap(Bitmap source, float max, float min) {
System.out.println("--------------------------------------");
float sourceHeight = source.getHeight();
float sourceWidth = source.getWidth();
float x, y, sourceX, sourceY;
if (sourceHeight > sourceWidth) {
y = sourceHeight;
x = sourceWidth;
} else {
y = sourceWidth;
x = sourceHeight;
}
sourceX = x;
sourceY = y;
System.out.println("y:" + y + " x:" + x + " sourceHeight:" + sourceHeight + " sourceWidth:" + sourceWidth);
boolean needCrop = false;
int crop = 0; // 1 = cropY 2=cropX
float scale = 1;
// 区分出需要裁剪的情况
if ((y > max && x < min) || (y > max && x > min && x < max && (y - max > x - min))) {
needCrop = true;
System.out.println("需要进行裁剪");
if (y > max && x < min) { // 1plan
System.out.println("plan 1");
y = max;
x = min;
scale = min / sourceX;
} else { // 2plan
System.out.println("plan 2");
y = max;
x = sourceY;
scale = max / sourceY;
}
} else {
System.out.println("不需要进行裁剪");
if (y < max && x > min && y < min && x < max) {// 3plan
System.out.println("plan 3");
y = sourceY;
x = sourceX;
} else if ((y > max && x > min && x < max && (y - max < x - min))) { // 4plan
System.out.println("plan 4");
y = max;
scale = max / sourceY;
x = scale * sourceX;
} else if (y > max && x > max) {
System.out.println("plan 5");
y = max;
scale = max / sourceY;
x = scale * sourceX;
} else if (y < min && x < min) {
System.out.println("plan 6");
x = min;
scale = min / sourceX;
y = scale * sourceY;
} else {
System.out.println("plan 7");
}
}
System.out.println("y:" + y + " x:" + x + " 是否裁剪:" + needCrop + " scale:" + scale);
System.out.println("--------------------------------------");
// 转X,Y ->targetWidth,targetHeight
float targetWidth, targetHeight;
if (sourceHeight > sourceWidth) {
targetHeight = y;
targetWidth = x;
} else {
targetHeight = x;
targetWidth = y;
}
System.out.println("targetHeight:" + targetHeight + " targetWidth:" + targetWidth);
Bitmap target = Bitmap.createBitmap((int) targetWidth, (int) targetHeight, getConfig(source));
Canvas canvas = new Canvas(target);
if (needCrop) {
if(sourceHeight > sourceWidth) {
float ty = (targetHeight - sourceHeight * scale) / 2;
System.out.println("竖向移动了：" + ty * scale);
canvas.translate(0, ty);
} else {
float tx = (targetWidth - sourceWidth * scale) / 2;
System.out.println("横向移动了：" + tx * scale);
canvas.translate(tx, 0);
}
}
canvas.scale(scale, scale);
Paint paint = new Paint(Paint.FILTER_BITMAP_FLAG | Paint.DITHER_FLAG);
canvas.drawBitmap(source, 0, 0, paint);
return target;
}
private static Bitmap.Config getConfig(Bitmap bitmap) {
Bitmap.Config config = bitmap.getConfig();
if (config == null) {
config = Bitmap.Config.ARGB_8888;
}
return config;
}
} 这个有什么实用性吗？
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