调整图像尺寸以保持纵横比

Question

我试图调整图像的大小并保持其宽高比，而位图mBitmap的尺寸为1200x539，因此我需要将其减小到大约1/3。

 mBitmap =  Bitmap.createBitmap (mContent.getWidth(), mContent.getHeight(), Bitmap.Config.RGB_565);;

                int H = (int)mBitmap.getHeight();      
                int W =(int)mBitmap.getWidth();            
                nBitmap = BitmapScaler.setBitmapScale(mBitmap, W,H);

我发现了Streets Of Boston提供的答案，并尝试在我的应用程序中使用它，但是我可能弄乱了变量，并且得到的图像与原始图像大小相同，有人可以告诉我如何正确实现此目标吗？

比例位图保持宽高比

代码运行无误，但返回的图像大小与原始图像相同！

public static Bitmap setBitmapScale(Bitmap originalImage, int width, int height){

            Bitmap background = Bitmap.createBitmap((int)width, (int)height, Config.ARGB_8888);
            float originalWidth = originalImage.getWidth(), originalHeight = originalImage.getHeight();
            Canvas canvas = new Canvas(background);
            float scale = width/originalWidth;
            float xTranslation = 0.0f, yTranslation = (height - originalHeight * scale)/2.0f;
            Matrix transformation = new Matrix();
            transformation.postTranslate(xTranslation, yTranslation);
            transformation.preScale(scale, scale);
            Paint paint = new Paint();
            paint.setFilterBitmap(true);
            canvas.drawBitmap(originalImage, transformation, paint);
            return background;
      }

Answer 1

以下是我出于个人目的使用的两个功能，这可能对您有帮助

/************************ Calculations for Image Sizing *********************************/ 
public Drawable ResizeImage (int imageID) { 

int newWidth = 1000; //This is new width which can be (1/3) * orignalWidth

double ratio = deviceWidth / imageWidth; 
int newImageHeight = (int) (imageHeight * ratio); 

Bitmap bMap = BitmapFactory.decodeResource(getResources(), imageID); 
Drawable drawable = new BitmapDrawable(this.getResources(),getResizedBitmap(bMap,newImageHeight,(int) deviceWidth)); 

return drawable; 
}

/************************ Resize Bitmap *********************************/ 
public Bitmap getResizedBitmap(Bitmap bm, int newHeight, int newWidth) { 

int width = bm.getWidth(); 
int height = bm.getHeight(); 

float scaleWidth = ((float) newWidth) / width; 
float scaleHeight = ((float) newHeight) / height; 

// create a matrix for the manipulation 
Matrix matrix = new Matrix(); 

// resize the bit map 
matrix.postScale(scaleWidth, scaleHeight); 

// recreate the new Bitmap 
Bitmap resizedBitmap = Bitmap.createBitmap(bm, 0, 0, width, height, matrix, false); 

return resizedBitmap; 
}