我一直在学习本教程，以了解如何在我正在开发的应用中实现Pinch Zoom和Pan功能 https://www.youtube.com/watch?v=BY8hLhu50po&list=PL9jCwTXYWjDJjDE_JxRozYGKGt8gbUXg7
基本上，他从图库中加载图像并将其显示在支持缩放/平移功能的图像视图中。
我想将图片预加载到图片视图中，而不是从图库中选择一个。理想情况下，我想从drawable加载图像。
教程的应用程序有很多额外的功能，我试图清除它们 首先它打开一个画廊。然后选择要显示的图像，并将其显示为mImageView内的缩略图。 在长按时，它隐藏了mImageView并在第二个图像视图中显示最大化的图像。 （MPinchZoomImageView）
此时，图像支持缩放和平移功能。
如果可以，我想跳过图库和第一个图像视图，只使用PinchZoom图像视图。我不确定我是怎么做的。
代码：
ImageViewMainActivity
public class ImageViewMainActivity extends AppCompatActivity {
ImageView mImageView;
PinchZoomImageView mPinchZoomImageView;
private Uri mImageUri;
private static final int REQUEST_OPEN_RESULT_CODE = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_image_view_main);
mImageView = (ImageView) findViewById(R.id.imageView);
mPinchZoomImageView = (PinchZoomImageView) findViewById(R.id.pinchZoomImageView);
mImageView.setOnLongClickListener(new View.OnLongClickListener() {
@Override
public boolean onLongClick(View v) {
pinchZoomPan();
return true;
}
});
Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);
intent.addCategory(Intent.CATEGORY_OPENABLE);
intent.setType("image/*");
startActivityForResult(intent, REQUEST_OPEN_RESULT_CODE); // pass it a context of 0
}
@Override
public void onWindowFocusChanged(boolean hasFocus) {
super.onWindowFocusChanged(hasFocus);
View decorView = getWindow().getDecorView();
if(hasFocus) {
decorView.setSystemUiVisibility(
View.SYSTEM_UI_FLAG_LAYOUT_STABLE
| View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
| View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
| View.SYSTEM_UI_FLAG_FULLSCREEN
| View.SYSTEM_UI_FLAG_IMMERSIVE_STICKY
| View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
);
}
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent resultData) {
if(requestCode == REQUEST_OPEN_RESULT_CODE && resultCode == RESULT_OK) {
if(resultData != null) {
mImageUri = resultData.getData();
Glide.with(this)
.load(mImageUri)
.into(mImageView);
}
}
}
private void pinchZoomPan() {
mPinchZoomImageView.setImageUri(mImageUri);
mImageView.setAlpha(0.f); // set mImageView invisible.
mPinchZoomImageView.setVisibility(View.VISIBLE);
}
}
PinchZoomImageView
public class PinchZoomImageView extends ImageView {
private Bitmap mBitmap;
private int mImageWidth;
private int mImageHeight;
private final static float mMinZoom = 1.f;
private final static float mMaxZoom = 4.f;
private float mScaleFactor = 1.f;
private ScaleGestureDetector mScaleGestureDetector;
private final static int NONE = 0;
private final static int PAN = 1;
private final static int ZOOM = 2;
private int mEventState;
private float mStartX = 0;
private float mStartY = 0;
private float mTranslateX = 0;
private float mTranslateY = 0;
private float mPreviousTranslateX = 0;
private float mPreviousTranslateY = 0;
private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
@Override
public boolean onScale(ScaleGestureDetector detector) {
mScaleFactor *= detector.getScaleFactor();
mScaleFactor = Math.max(mMinZoom, Math.min(mMaxZoom, mScaleFactor));
// invalidate();
// requestLayout();
return super.onScale(detector);
}
}
public PinchZoomImageView(Context context, AttributeSet attrs) {
super(context, attrs);
mScaleGestureDetector = new ScaleGestureDetector(getContext(), new ScaleListener());
}
@Override
public boolean onTouchEvent(MotionEvent event) {
switch(event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
mEventState = PAN;
mStartX = event.getX() - mPreviousTranslateX;
mStartY = event.getY() - mPreviousTranslateY;
break;
case MotionEvent.ACTION_UP:
mEventState = NONE;
mPreviousTranslateX = mTranslateX;
mPreviousTranslateY = mTranslateY;
break;
case MotionEvent.ACTION_MOVE:
mTranslateX = event.getX() - mStartX;
mTranslateY = event.getY() - mStartY;
break;
case MotionEvent.ACTION_POINTER_DOWN:
mEventState = ZOOM;
break;
}
mScaleGestureDetector.onTouchEvent(event);
if((mEventState == PAN && mScaleFactor != mMinZoom) || mEventState == ZOOM) { // called under the condition that window is zoomed i
invalidate();
requestLayout();
}
return true;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int imageWidth = MeasureSpec.getSize(widthMeasureSpec);
int imageHeight = MeasureSpec.getSize(heightMeasureSpec);
int scaledWidth = Math.round(mImageWidth * mScaleFactor);
int scaledHeight = Math.round(mImageHeight * mScaleFactor);
setMeasuredDimension(
Math.min(imageWidth, scaledWidth),
Math.min(imageHeight, scaledHeight)
);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.save();
canvas.scale(mScaleFactor, mScaleFactor);
// canvas.scale(mScaleFactor, mScaleFactor, mScaleGestureDetector.getFocusX(), mScaleGestureDetector.getFocusY());
if((mTranslateX * -1) < 0) {
mTranslateX = 0;
} else if ((mTranslateX * -1) > mImageWidth * mScaleFactor - getWidth()) {
mTranslateX = (mImageWidth * mScaleFactor - getWidth()) * -1;
}
if((mTranslateY * -1) < 0) {
mTranslateY = 0;
} else if ((mTranslateY * -1) > mImageHeight * mScaleFactor - getHeight()) {
mTranslateY = (mImageHeight * mScaleFactor - getHeight()) * -1;
}
canvas.translate(mTranslateX/mScaleFactor, mTranslateY/mScaleFactor);
canvas.drawBitmap(mBitmap, 0, 0, null);
canvas.restore();
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
}
public void setImageUri(Uri uri) {
try {
Bitmap bitmap = MediaStore.Images.Media.getBitmap(getContext().getContentResolver(), uri);
float aspecRatio = (float) bitmap.getHeight() / (float) bitmap.getWidth();
DisplayMetrics displayMetrics = getResources().getDisplayMetrics();
mImageWidth = displayMetrics.widthPixels;
mImageHeight = Math.round(mImageWidth * aspecRatio);
mBitmap = Bitmap.createScaledBitmap(bitmap, mImageWidth, mImageHeight, false);
invalidate();
requestLayout();
} catch (IOException e) {
e.printStackTrace();
}
}
}
XML
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="mobapptut.com.imageviewer.ImageViewMainActivity">
<ImageView
android:layout_width="200dp"
android:layout_height="150dp"
android:id="@+id/imageView"
android:layout_centerInParent="true" />
<mobapptut.com.imageviewer.PinchZoomImageView
android:visibility="invisible"
android:id="@+id/pinchZoomImageView"
android:layout_centerInParent="true"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</RelativeLayout>
谢谢