为什么位图转换为Base64字符串表示的Andr​​oid黑色背景上的WebView？ [英] Why Bitmap to Base64 String showing black background on webview in android?

问题描述

我使用的是code，结合到图像转换成1使用画布。我表明，图像的ImageView它看起来不错。但是，当我试图表明，进入web视图显示它的背景黑色正确的图像。我试图改变在HTML中的背景颜色，但它不会变色。或使透明。任何人都可以帮忙吗？ 结果是这里上面的影像是在ImageView的下方是web视图。

I am using a code that combine to images into 1 by using canvas . I show that image to ImageView it looks fine. But when I try to show that into WebView it show background black to right that image. I try to change the background color in HTML but it not change color. or make transparent. Can anyone help? Result is here The above image is in ImageView and below is in WebView.

public class MyBimapTest extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    ImageView img1 = (ImageView) findViewById(R.id.ImageView01);

    img1.setVisibility(View.INVISIBLE);
    Drawable dra1 = img1.getDrawable();
    Bitmap map1 = ((BitmapDrawable) dra1).getBitmap();
    ImageView img2 = (ImageView) findViewById(R.id.ImageView02);
    img2.setVisibility(View.INVISIBLE);
    Drawable dra2 = img2.getDrawable();
    Bitmap map2 = ((BitmapDrawable) dra2).getBitmap();

    // ***
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    map1.compress(Bitmap.CompressFormat.JPEG, 100, baos);

    byte[] b = baos.toByteArray();
    String abc = Base64.encodeBytes(b);

    byte[] byt = null;
    try {
        byt = Base64.decode(abc);
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    map1 = BitmapFactory.decodeByteArray(byt, 0, byt.length);

    // ***
    Bitmap map = combineImages(map1, map2);
    ByteArrayOutputStream bbb = new ByteArrayOutputStream();
    map.compress(Bitmap.CompressFormat.JPEG, 100, bbb);

    byte[] bit = bbb.toByteArray();

    String imgToString = Base64.encodeBytes(bit);

    String imgTag = "<img src='data:image/jpg;base64," + imgToString
            + "' align='left' bgcolor='ff0000'/>";

    WebView webView = (WebView) findViewById(R.id.storyView);
    webView.loadData(imgTag, "text/html", "utf-8");
    Drawable end = new BitmapDrawable(map);

    ImageView img3 = (ImageView) findViewById(R.id.ImageView03);
    img3.setImageBitmap(map);
}

public Bitmap combineImages(Bitmap c, Bitmap s) { 
    Bitmap cs = null;
    int width, height = 0;

    width = c.getWidth() + (s.getWidth() / 2);
    height = c.getHeight() + (s.getHeight() / 2);

    cs = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);

    Canvas comboImage = new Canvas(cs);

    comboImage.drawBitmap(c, 0f, 0f, null);
    comboImage.drawBitmap(s, c.getWidth() - (s.getWidth() / 2), c
            .getHeight()
            - (s.getHeight() / 2), null);
    return cs;
}

}

推荐答案

在 JPEG 格式不支持Alpha透明度，这就是为什么当你转换透明背景变成黑色您的原始图像 JPEG 。

The JPEG format does not support alpha transparency, which is why the transparent background becomes black when you convert your original image to JPEG.

使用了 PNG 格式来代替：

 map1.compress(Bitmap.CompressFormat.PNG, 100, baos); 

和

String imgTag = "<img src='data:image/png;base64," + imgToString               
    + "' align='left' bgcolor='ff0000'/>";   

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