1.主要算法实现
<pre>
private File thirdCompress(@NonNull File file) {
String thumb = mCacheDir.getAbsolutePath() + File.separator + (TextUtils.isEmpty(filename) ? System.currentTimeMillis() : filename);
double size;
String filePath = file.getAbsolutePath();
int angle = getImageSpinAngle(filePath);
int width = getImageSize(filePath)[0];
int height = getImageSize(filePath)[1];
int thumbW = width % 2 == 1 ? width + 1 : width;
int thumbH = height % 2 == 1 ? height + 1 : height;
width = thumbW > thumbH ? thumbH : thumbW;
height = thumbW > thumbH ? thumbW : thumbH;
double scale = ((double) width / height);
if (scale <= 1 && scale > 0.5625) {
if (height < 1664) {
if (file.length() / 1024 < 150) return file;
size = (width * height) / Math.pow(1664, 2) * 150;
size = size < 60 ? 60 : size;
} else if (height >= 1664 && height < 4990) {
thumbW = width / 2;
thumbH = height / 2;
size = (thumbW * thumbH) / Math.pow(2495, 2) * 300;
size = size < 60 ? 60 : size;
} else if (height >= 4990 && height < 10240) {
thumbW = width / 4;
thumbH = height / 4;
size = (thumbW * thumbH) / Math.pow(2560, 2) * 300;
size = size < 100 ? 100 : size;
} else {
int multiple = height / 1280 == 0 ? 1 : height / 1280;
thumbW = width / multiple;
thumbH = height / multiple;
size = (thumbW * thumbH) / Math.pow(2560, 2) * 300;
size = size < 100 ? 100 : size;
}
} else if (scale <= 0.5625 && scale > 0.5) {
if (height < 1280 && file.length() / 1024 < 200) return file;
int multiple = height / 1280 == 0 ? 1 : height / 1280;
thumbW = width / multiple;
thumbH = height / multiple;
size = (thumbW * thumbH) / (1440.0 * 2560.0) * 400;
size = size < 100 ? 100 : size;
} else {
int multiple = (int) Math.ceil(height / (1280.0 / scale));
thumbW = width / multiple;
thumbH = height / multiple;
size = ((thumbW * thumbH) / (1280.0 * (1280 / scale))) * 500;
size = size < 100 ? 100 : size;
}
return compress(filePath, thumb, thumbW, thumbH, angle, (long) size);
}
</br>
/**
- obtain the thumbnail that specify the size
- @param imagePath the target image path
- @param width the width of thumbnail
- @param height the height of thumbnail
- @return {@link Bitmap}
*/
private Bitmap compress(String imagePath, int width, int height) {
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(imagePath, options);
int outH = options.outHeight;
int outW = options.outWidth;
int inSampleSize = 1;
if (outH > height || outW > width) {
int halfH = outH / 2;
int halfW = outW / 2;
while ((halfH / inSampleSize) > height && (halfW / inSampleSize) > width) {
inSampleSize *= 2;
}
}
options.inSampleSize = inSampleSize;
options.inJustDecodeBounds = false;
int heightRatio = (int) Math.ceil(options.outHeight / (float) height);
int widthRatio = (int) Math.ceil(options.outWidth / (float) width);
if (heightRatio > 1 || widthRatio > 1) {
if (heightRatio > widthRatio) {
options.inSampleSize = heightRatio;
} else {
options.inSampleSize = widthRatio;
}
options.inJustDecodeBounds = false;
return BitmapFactory.decodeFile(imagePath, options);
}
</pre>
