我正在编写 Android 代码,有一个 ImageView。我想将其 scaletype 设置为 topcrop。虽然我在选项中找到了 centercrop,但这不是我的要求。我该怎么做?
自定义 Android ImageView,用于对所包含的 drawable 进行顶部裁剪缩放。
import android.content.Context;
import android.graphics.Matrix;
import android.widget.ImageView;
/**
* ImageView to display top-crop scale of an image view.
*
* @author Chris Arriola
*/
public class TopCropImageView extends ImageView {
public TopCropImageView(Context context) {
super(context);
setScaleType(ScaleType.MATRIX);
}
@Override
protected boolean setFrame(int l, int t, int r, int b) {
final Matrix matrix = getImageMatrix();
float scale;
final int viewWidth = getWidth() - getPaddingLeft() - getPaddingRight();
final int viewHeight = getHeight() - getPaddingTop() - getPaddingBottom();
final int drawableWidth = getDrawable().getIntrinsicWidth();
final int drawableHeight = getDrawable().getIntrinsicHeight();
if (drawableWidth * viewHeight > drawableHeight * viewWidth) {
scale = (float) viewHeight / (float) drawableHeight;
} else {
scale = (float) viewWidth / (float) drawableWidth;
}
matrix.setScale(scale, scale);
setImageMatrix(matrix);
return super.setFrame(l, t, r, b);
}
}
我只是希望有一个不需要太多额外工作的临时解决方案。试试这个。
<ImageView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:scaleType="centerCrop"
android:scrollY="-100dp"
android:id="@+id/poster"
/>
scrollY可以上下拉动您的图像。试试不同的dp,您会找到正确的尺寸。
scaleType
设置为 matrix
,并为 ImageView
设置一个自定义矩阵即可。修正版本:
import android.content.Context
import android.graphics.Matrix
import android.util.AttributeSet
import androidx.appcompat.widget.AppCompatImageView
class TopCropImageView @JvmOverloads constructor(
context: Context,
attrs: AttributeSet? = null,
defStyleAttr: Int = 0,
) : AppCompatImageView(context, attrs, defStyleAttr) {
init {
scaleType = ScaleType.MATRIX
}
override fun setFrame(l: Int, t: Int, r: Int, b: Int): Boolean {
super.setFrame(l, t, r, b)
val matrix = Matrix()
val scale: Float
val viewWidth: Int = width - paddingLeft - paddingRight
val viewHeight: Int = height - paddingTop - paddingBottom
val drawableWidth: Int = drawable.intrinsicWidth
val drawableHeight: Int = drawable.intrinsicHeight
scale = if (drawableWidth * viewHeight > drawableHeight * viewWidth) {
viewHeight.toFloat() / drawableHeight.toFloat()
} else {
viewWidth.toFloat() / drawableWidth.toFloat()
}
matrix.setScale(scale, scale)
imageMatrix = matrix
return true
}
}