如何在代码中使用毕加索设置背景图像答案

【问题标题】：How do I set background image with picasso in code如何在代码中使用毕加索设置背景图像
【发布时间】：2015-06-28 22:01:53
【问题描述】：

我知道 picasso 会将图像加载到 imageview 等中，但是如何使用 picasso 设置我的布局背景图像？

我的代码：

public class MainActivity extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        RelativeLayout relativeLayout = (RelativeLayout) findViewById(R.id.relativelayout);
        relativeLayout.setBackgroundResource(R.drawable.table_background);
        Picasso.with(MainActivity.this)
                .load(R.drawable.table_background)
                .resize(200, 200)
                .into(relativeLayout);
        return relativeLayout;
    }

我在这里给出的任何错误都表明它无法解决。我有一个 ScrollView 和相关布局。

【问题讨论】：

标签： java android picasso android-scrollview android-relativelayout

【解决方案1】：

使用毕加索的回调

    Picasso.with(getActivity()).load(R.drawable.table_background).into(new Target(){

  @Override
  public void onBitmapLoaded(Bitmap bitmap, LoadedFrom from) {
     mainLayout.setBackground(new BitmapDrawable(context.getResources(), bitmap));
  }

  @Override
  public void onBitmapFailed(final Drawable errorDrawable) {
      Log.d("TAG", "FAILED");
  }

  @Override
  public void onPrepareLoad(final Drawable placeHolderDrawable) {
      Log.d("TAG", "Prepare Load");
  }      
})

更新：

也请检查this。正如评论中提到的@OlivierH。

【讨论】：

小心：如this answer、Picasso holds a weak reference to Target objects, hence it is likely to be garbage collected.中所述
@OlivierH 。我已经更新了答案。感谢您指出。
另一个好的解决方案是将目标存储在视图标签中作为强引用。我在这里找到了解决方案，这对我有用：stackoverflow.com/questions/24180805/…
什么是mainLayout？
@FernandoUrban 这是您要设置位图的布局。

【解决方案2】：

创建自定义转换的最佳方式，例如填充颜色：

public class BackgroundColorTransform implements Transformation {

    @ColorInt int mFillColor;

    public BackgroundColorTransform(@ColorInt int color) {
        super();
        mFillColor = color;
    }

    @Override
    public Bitmap transform(Bitmap bitmap) {
        // Create another bitmap that will hold the results of the filter.
        int width = bitmap.getWidth();
        int height = bitmap.getHeight();
        Bitmap out = Bitmap.createBitmap(width, height, bitmap.getConfig());
        Canvas canvas = new Canvas(out);
        Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        canvas.drawColor(mFillColor);
        canvas.drawBitmap(bitmap, 0f, 0f, paint);
        bitmap.recycle();
        return out;
    }

    @Override
    public String key() {
        return "BackgroundColorTransform:"+mFillColor;
    }

}

用法：

mPicasso.load(imageUrl)
               .transform(new BackgroundColorTransform(ContextCompat.getColor(getContext(),R.color.black)))
                .into(mLogoImageView);

如果您想添加 vectorDrawable 图像，请使用 Transformation ：

public class AddVectorDrawableTransform implements Transformation {

    private Drawable mDrawable;
    @ColorInt int mTintColor;

    public AddVectorDrawableTransform(Drawable drawable, @ColorInt int tintColor) {
        super();
        mDrawable = drawable;
        mTintColor = tintColor;
    }

    @Override
    public Bitmap transform(Bitmap bitmap) {
        // Create another bitmap that will hold the results of the filter.
        int width = bitmap.getWidth();
        int height = bitmap.getHeight();
        Bitmap out = Bitmap.createBitmap(width, height, bitmap.getConfig());
        Canvas canvas = new Canvas(out);
        Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        canvas.drawBitmap(bitmap, 0f, 0f, paint);
        Drawable drawable = mDrawable.mutate();
        drawable = DrawableCompat.wrap(drawable);
        DrawableCompat.setTint(drawable, mTintColor);
        DrawableCompat.setTintMode(drawable, PorterDuff.Mode.SRC_IN);
//        mDrawable.setColorFilter( mTintColor, PorterDuff.Mode.MULTIPLY);
        drawable.setBounds(width/4, height/4, 3*width/4, 3*height/4);
        drawable.draw(canvas);
        bitmap.recycle();
        return out;
    }

    @Override
    public String key() {
        return "AddDrawableTransform:"+mDrawable+", "+mTintColor;
    }

}

【讨论】：