[英]ImageView to scale to fixed height, but crop excess width
我希望我的ImageView
以特定方式擴展:
ImageView
的高度圖片勝於千言萬語,下面是我希望我的ImageView
表現如何的表示。 假設它的高度固定為 100dp,寬度為match_parent
。
注意
CROP_CENTER
。ImageView
高度,表現得像FIT_CENTER
我懷疑我需要scaleType:matrix
,但在那之后我迷路了。 如何確保圖像適合 Y,但裁剪 X?
在xml中,使用:
android:scaleType="centerCrop"
android:adjustViewBounds="true"
在朋友Carlos Robles和pskink的幫助下,想出了以下自定義ImageView
:
public class FitYCropXImageView extends ImageView {
boolean done = false;
@SuppressWarnings("UnusedDeclaration")
public FitYCropXImageView(Context context) {
super(context);
setScaleType(ScaleType.MATRIX);
}
@SuppressWarnings("UnusedDeclaration")
public FitYCropXImageView(Context context, AttributeSet attrs) {
super(context, attrs);
setScaleType(ScaleType.MATRIX);
}
@SuppressWarnings("UnusedDeclaration")
public FitYCropXImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
setScaleType(ScaleType.MATRIX);
}
private final RectF drawableRect = new RectF(0, 0, 0,0);
private final RectF viewRect = new RectF(0, 0, 0,0);
private final Matrix m = new Matrix();
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
if (done) {
return;//Already fixed drawable scale
}
final Drawable d = getDrawable();
if (d == null) {
return;//No drawable to correct for
}
int viewHeight = getMeasuredHeight();
int viewWidth = getMeasuredWidth();
int drawableWidth = d.getIntrinsicWidth();
int drawableHeight = d.getIntrinsicHeight();
drawableRect.set(0, 0, drawableWidth, drawableHeight);//Represents the original image
//Compute the left and right bounds for the scaled image
float viewHalfWidth = viewWidth / 2;
float scale = (float) viewHeight / (float) drawableHeight;
float scaledWidth = drawableWidth * scale;
float scaledHalfWidth = scaledWidth / 2;
viewRect.set(viewHalfWidth - scaledHalfWidth, 0, viewHalfWidth + scaledHalfWidth, viewHeight);
m.setRectToRect(drawableRect, viewRect, Matrix.ScaleToFit.CENTER /* This constant doesn't matter? */);
setImageMatrix(m);
done = true;
requestLayout();
}
}
如果使用scaleType:matrix
,則需要創建自己的Matrix並通過setImageMatrix(Matrix)
將其指定給視圖,或者在customImageView的hen onMEasure方法中手動修改矩陣。
public class MyImageView extends ImageView {
boolean done=false;
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
if (done)
return;
final Drawable d = getDrawable();
final int drawableW = d.getIntrinsicWidth();
final int drawableH = d.getIntrinsicHeight();
float ratio = drawableW / drawableH;
//int width = getMeasuredWidth();
int height = getMeasuredHeight();
float scale=height/drawableH;
Matrix m = getImageMatrix();
float[] f = new float[9];
m.getValues(f);
f[Matrix.MSCALE_X]=scale;
f[Matrix.MSCALE_Y]=scale;
m.setValues(f);
done = true;
requestLayout();
}
}
LinearLayout ll = new LinearLayout(this);
ll.setOrientation(LinearLayout.VERTICAL);
LayoutParams params;
final ImageView iv0 = new ImageView(this);
//iv0.setBackgroundColor(0xffff0000);
params = new LayoutParams(LayoutParams.MATCH_PARENT, 100);
ll.addView(iv0, params);
final ImageView iv1 = new ImageView(this);
//iv1.setBackgroundColor(0xff00ff00);
params = new LayoutParams(60, 100);
ll.addView(iv1, params);
setContentView(ll);
Runnable action = new Runnable() {
@Override
public void run() {
Drawable d = getResources().getDrawable(R.drawable.layer0);
int dw = d.getIntrinsicWidth();
int dh = d.getIntrinsicHeight();
RectF src = new RectF(0, 0, dw, dh);
ImageView[] iviews = {iv0, iv1};
for (int i = 0; i < iviews.length; i++) {
ImageView iv = iviews[i];
iv.setImageDrawable(d);
iv.setScaleType(ScaleType.MATRIX);
float h = iv.getHeight();
float w = iv.getWidth();
float cx = w / 2;
float scale = h / dh;
float deltaw = dw * scale / 2;
RectF dst = new RectF(cx - deltaw, 0, cx + deltaw, h);
Matrix m = new Matrix();
m.setRectToRect(src, dst, ScaleToFit.FILL);
iv.setImageMatrix(m);
}
}
};
iv1.post(action);
如果要顯示圖像的中心,請使用:
android:scaleType="centerCrop"
android:adjustViewBounds="true"
如果要顯示圖像的邊緣而不是中心,請使用:
android:scaleType="matrix"
android:adjustViewBounds="true"
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