Question

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上使用的图像。这一切都很好，但是当我做的时候

imageView.setImageBitmap(bitmap);

显示新图像，但基本上垂直居中于页面上，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>

如果我没有调用setBitmap，那么默认图片（@ drawable / jeepfront）显示就好了，在页面顶部我可以看到按钮。

有什么想法吗？我在Android上有点新手，但从1.0开始就使用Java。

谢谢，大卫

Answer 1

您可以通过实现以下代码来实现此目的。

/**
 * 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);
}

public static Bitmap scaleAssetImage(Bitmap bitmap, View view, Context context)方法会接受您的bitmap和ImageView，并会根据LayoutParams尺寸设置bitmap。

android图像位置错误

1 个答案: