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帮助！

我有一个奇怪的问题。我正在编写一个 Android 应用程序，允许用户选择要在下一页使用的图像。这一切都很好，但是当我这样做时

imageView.setImageBitmap(bitmap);

显示了新图像，但基本上在页面上垂直居中，隐藏了我在设计时放置在页面上的按钮。布局如下所示：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:src="@drawable/jeepfront" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/imageView"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="46dp"
        android:text="Button" />

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/button1"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="43dp"
        android:text="Picture resized/cropped with any buttons"
        android:textAppearance="?android:attr/textAppearanceLarge" />

</RelativeLayout>

如果我不调用 setBitmap，那么默认图片 (@drawable/jeepfront) 显示得很好，在页面顶部，我可以看到按钮。

有任何想法吗？我对 Android 有点陌生，但从 1.0 开始就一直在使用 Java。

谢谢，大卫

4

1 回答 1

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您可以通过实现以下代码来实现这一点。

/**
 * Scales image bitmap to fit in correctly in the view. The
 * {@link LayoutParams} for the view in which the bitmap to be rendered is
 * set here
 * 
 * @param bitmap
 *            the {@link Bitmap} object to be scaled
 * @param view
 *            the view in which the bitmap will be rendered
 * @param context
 *            the context being used for invoking the method dpToPx(int,
 *            Context)
 * @return a scaled {@link Bitmap} object for the {@link View} obejct
 *         provided
 */
public static Bitmap scaleAssetImage(Bitmap bitmap, View view,
        Context context) {
    int width = bitmap.getWidth();
    int height = bitmap.getHeight();
    int bounding = dpToPx(250, context);

    float xScale = ((float) bounding) / width;
    float yScale = ((float) bounding) / height;
    float scale = (xScale <= yScale) ? xScale : yScale;

    Matrix matrix = new Matrix();
    matrix.postScale(scale, scale);
    Bitmap scaledBitmap = Bitmap.createBitmap(bitmap, 0, 0, width, height,
            matrix, true);
    width = scaledBitmap.getWidth();
    height = scaledBitmap.getHeight();
    RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) view
            .getLayoutParams();
    params.width = width;
    params.height = height;
    view.setLayoutParams(params);
    return scaledBitmap;
}

/**
 * Converts dp to pixel
 * 
 * @param dpValue
 *            the integer value to be scaled into pixels
 * @param context
 *            the context being used for accessing resources
 * @return the converted value
 */
private static int dpToPx(int dpValue, Context context) {
    float density = context.getResources().getDisplayMetrics().density;
    return Math.round((float) dpValue * density);
}

该public static Bitmap scaleAssetImage(Bitmap bitmap, View view, Context context)方法将接受您bitmap的和您的ImageView，并将LayoutParams根据bitmap大小设置。

于 2014-03-25T03:21:34.443 回答