前言：刚才看微博，看到很多长图。一时兴起，想通过代码制作一张长图并展示。我的思路是利用Canvas将多张照片依次合成，并在外层套用一个ScrollView展示图片以及保存本地。
效果图如下：
关键代码：
public static Bitmap newBitmap(Bitmap bmp1, Bitmap bmp2) {
Bitmap retBmp;
int width =bmp1.getWidth() ;
if (bmp2.getWidth() != width) {
//以第一张图片的宽度为标准，对第二张图片进行缩放。
int h2 = bmp2.getHeight() * width / bmp2.getWidth();
retBmp = Bitmap.createBitmap(width, bmp1.getHeight() + h2, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(retBmp);
Bitmap newSizeBmp2 = resizeBitmap(bmp2, width, h2);
canvas.drawBitmap(bmp1, 0, 0, null);
canvas.drawBitmap(newSizeBmp2, 0, bmp1.getHeight(), null);
} else {
//两张图片宽度相等，则直接拼接。
retBmp = Bitmap.createBitmap(width, bmp1.getHeight() + bmp2.getHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(retBmp);
canvas.drawBitmap(bmp1, 0, 0, null);
canvas.drawBitmap(bmp2, 0, bmp1.getHeight(), null);
}
img.setImageBitmap(retBmp);
return retBmp;
}
public static Bitmap resizeBitmap(Bitmap bitmap, int newWidth, int newHeight) {
float scaleWidth = ((float) newWidth) / bitmap.getWidth();
float scaleHeight = ((float) newHeight) / bitmap.getHeight();
Matrix matrix = new Matrix();
matrix.postScale(scaleWidth, scaleHeight);
Bitmap bmpScale = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
return bmpScale;
}
/**
* 保存图片到文件File。
*
* @param src 源图片
* @param file 要保存到的文件
* @param format 格式
* @param recycle 是否回收
* @return true 成功 false 失败
*/
public static boolean save(Bitmap src, File file, Bitmap.CompressFormat format, boolean recycle) {
if (isEmptyBitmap(src))
return false;
OutputStream os;
boolean ret = false;
try {
os = new BufferedOutputStream(new FileOutputStream(file));
ret = src.compress(format, 100, os);
if (recycle && !src.isRecycled())
src.recycle();
} catch (IOException e) {
e.printStackTrace();
}
return ret;
}
/**
* Bitmap对象是否为空。
*/
public static boolean isEmptyBitmap(Bitmap src) {
return src == null || src.getWidth() == 0 || src.getHeight() == 0;
}
最后，完整项目源码地址