如何根据黑莓的高度和宽度调整图像大小

Question

如何根据黑莓屏幕的高度和宽度调整来自 HTTP 服务器的图像的大小？请有任何解决方案。

Answer 1

使用参数 Disply.getWidth() 和 Display.getHieght() 试试这个。

package CustomizedField;

import net.rim.device.api.system.Bitmap;
import net.rim.device.api.ui.Color;
import net.rim.device.api.ui.Graphics;

public class GPATools
{
    /**
     * Resizes a bitmap with an alpha channel (transparency) 
     * without the artifacts introduced
     *   by <code>scaleInto()</code>.
     *
     * @param bmpSrc        Source Bitmap
     * @param nWidth        New Width
     * @param nHeight       New Height
     * @param nFilterType   Filter quality to use. Can be          
     *                           <code>Bitmap.FILTER_LANCZOS</code>,
     *                           <code>Bitmap.FILTER_BILINEAR</code> or
     *                           <code>Bitmap.FILTER_BOX</code>.
     * @param nAspectRatio  Specifies how the picture is resized. Can be
     *                           <code>Bitmap.SCALE_TO_FIT</code>,
     *                           <code>Bitmap.SCALE_TO_FILL</code> or
     *                           <code>Bitmap.SCALE_STRETCH</code>.
     * @return              The resized Bitmap in a new object.
     */
    public static Bitmap ResizeTransparentBitmap(Bitmap bmpSrc, 
     int nWidth, int nHeight, int nFilterType, int nAspectRatio)
    {
        if(bmpSrc== null)
            return null;

        //Get the original dimensions of the bitmap
        int nOriginWidth = bmpSrc.getWidth();
        int nOriginHeight = bmpSrc.getHeight();
        if(nWidth == nOriginWidth && nHeight == nOriginHeight)
            return bmpSrc;

        //Prepare a drawing bitmap and graphic object
        Bitmap bmpOrigin = new Bitmap(nOriginWidth, nOriginHeight);
        Graphics graph = Graphics.create(bmpOrigin);

        //Create a line of transparent pixels for later use
        int[] aEmptyLine = new int[nWidth];
        for(int x = 0; x < nWidth; x++)
            aEmptyLine[x] = 0x00000000;
        //Create two scaled bitmaps
        Bitmap[] bmpScaled = new Bitmap[2];
        for(int i = 0; i < 2; i++)
        {
            //Draw the bitmap on a white background first, 
            //then on a black background
            graph.setColor((i == 0) ? Color.WHITE : Color.BLACK);
            graph.fillRect(0, 0, nOriginWidth, nOriginHeight);
            graph.drawBitmap(0, 0, nOriginWidth, nOriginHeight, bmpSrc, 0, 0);

            //Create a new bitmap with the desired size
            bmpScaled[i] = new Bitmap(nWidth, nHeight);
            if(nAspectRatio == Bitmap.SCALE_TO_FIT)
            {
                //Set the alpha channel of all pixels to 0 
                //to ensure transparency is
                //applied around the picture, if needed by the transformation
                for(int y = 0; y < nHeight; y++)
                    bmpScaled[i].setARGB(aEmptyLine, 0, nWidth, 
                      0, y, nWidth, 1);
            }

            //Scale the bitmap
            bmpOrigin.scaleInto(bmpScaled[i], nFilterType, nAspectRatio);
        }

        //Prepare objects for final iteration
        Bitmap bmpFinal = bmpScaled[0];
        int[][] aPixelLine = new int[2][nWidth];

        //Iterate every line of the two scaled bitmaps
        for(int y = 0; y < nHeight; y++)
        {
            bmpScaled[0].getARGB(aPixelLine[0], 0, nWidth, 0, y, nWidth, 1);
            bmpScaled[1].getARGB(aPixelLine[1], 0, nWidth, 0, y, nWidth, 1);

            //Check every pixel one by one
            for(int x = 0; x < nWidth; x++)
            {
                //If the pixel was untouched (alpha channel still at 0), 
                //keep it transparent
                if(((aPixelLine[0][x] >> 24) & 0xff) == 0)
                    aPixelLine[0][x] = 0x00000000;
                else
                {
                    //Compute the alpha value based on the difference 
                    //of intensity in the red channel
                    int nAlpha = ((aPixelLine[1][x] >> 16) & 0xff) -
                                    ((aPixelLine[0][x] >> 16) & 0xff) + 255;
                    if(nAlpha == 0)
                        aPixelLine[0][x] = 0x00000000; //Completely transparent
                    else if(nAlpha >= 255)
                        aPixelLine[0][x] |= 0xff000000; //Completely opaque
                    else
                    {
                        //Compute the value of the each channel one by one
                        int nRed = ((aPixelLine[0][x] >> 16 ) & 0xff);
                        int nGreen = ((aPixelLine[0][x] >> 8 ) & 0xff);
                        int nBlue = (aPixelLine[0][x] & 0xff);

                        nRed = (int)(255 + 
                          (255.0 * ((double)(nRed-255)/(double)nAlpha)));
                        nGreen = (int)(255 + 
                          (255.0 * ((double)(nGreen-255)/(double)nAlpha)));
                        nBlue = (int)(255 + 
                          (255.0 * ((double)(nBlue-255)/(double)nAlpha)));

                        if(nRed < 0) nRed = 0;
                        if(nGreen < 0) nGreen = 0;
                        if(nBlue < 0) nBlue = 0;
                        aPixelLine[0][x] = nBlue | (nGreen<<8) | 
                          (nRed<<16) | (nAlpha<<24);
                    }
                }
            }

            //Change the pixels of this line to their final value
            bmpFinal.setARGB(aPixelLine[0], 0, nWidth, 0, y, nWidth, 1);
        }
        return bmpFinal;
    }
} 

Answer 2

从图像的字节创建一个EncodedImage。

使用Display.getHeight() 和Display.getWidth() 获取显示器的尺寸。

然后使用EncodedImage.scaleImage32() 调整大小。检查this post 了解具体情况。

Answer 3

这是将图像调整为任意大小的方法：

public  EncodedImage resizeImage(EncodedImage image, int newWidth, int newHeight) 
            {
                        int scaleFactorX = Fixed32.div(Fixed32.toFP(image.getWidth()), Fixed32.toFP(newWidth));
                        int scaleFactorY = Fixed32.div(Fixed32.toFP(image.getHeight()), Fixed32.toFP(newHeight));
                        return image.scaleImage32(scaleFactorX, scaleFactorY);
            }

您只需传递宽度和高度 - 您想要调整图像大小的参数。

您可以分别使用Display.getWidth() 和Display.getHeight() 获得显示屏幕的宽度和高度。