Im folgenden Code habe ich etwas namens RegionView( git) erstellt ) erstellt, einen wiederverwendbaren Container, der für die Verwaltung von Drag & Zoom-Vorgängen für jedes seiner verschachtelten untergeordneten Elemente verantwortlich ist.
Hier manipulieren wir die topund leftKoeffizienten eines Kindes View, LayoutParamsum die Bewegung um das Diagramm zu simulieren. Indem wir die Interpretation der Handhabung entkoppeln, die als Drag-Operation verstanden wird und als Scale-Operation bestimmt wird, können wir ein Kind zuverlässig manipulieren View.
package com.zonal.regionview;
import android.annotation.TargetApi;
import android.content.Context;
import android.os.Build;
import android.os.Vibrator;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
import android.widget.RelativeLayout;
import java.util.HashMap;
import java.util.Map;
/**
* Created by Alexander Thomas (@Cawfree) on 20/07/2017.
*/
/** Enables users to customize Regions Of Interest on a Canvas. */
public class RegionView extends RelativeLayout implements View.OnTouchListener, GestureDetector.OnGestureListener, ScaleGestureDetector.OnScaleGestureListener {
/* Member Variables. */
private final GestureDetector mGestureDetector;
private final ScaleGestureDetector mScaleGestureDetector;
private final Map<Integer, View> mViewMap;
private boolean mScaling;
private float mScale;
private boolean mWrapContent;
private boolean mDropOnScale;
public RegionView(Context context) {
// Implement the Parent.
super(context);
// Initialize Member Variables.
this.mGestureDetector = new GestureDetector(context, this);
this.mViewMap = new HashMap<>();
this.mScaleGestureDetector = new ScaleGestureDetector(context, this);
this.mScaling = false;
this.mScale = Float.NaN;
this.mWrapContent = false;
this.mDropOnScale = false;
// Register ourself as the OnTouchListener.
this.setOnTouchListener(this);
}
public RegionView(Context context, @Nullable AttributeSet attrs) {
// Implement the Parent.
super(context, attrs);
// Initialize Member Variables.
this.mGestureDetector = new GestureDetector(context, this);
this.mViewMap = new HashMap<>();
this.mScaleGestureDetector = new ScaleGestureDetector(context, this);
this.mScaling = false;
this.mWrapContent = false;
this.mDropOnScale = false;
// Register ourself as the OnTouchListener.
this.setOnTouchListener(this);
}
public RegionView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
// Implement the Parent.
super(context, attrs, defStyleAttr);
// Initialize Member Variables.
this.mGestureDetector = new GestureDetector(context, this);
this.mViewMap = new HashMap<>();
this.mScaleGestureDetector = new ScaleGestureDetector(context, this);
this.mScaling = false;
this.mWrapContent = false;
this.mDropOnScale = false;
// Register ourself as the OnTouchListener.
this.setOnTouchListener(this);
}
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
public RegionView(Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
// Implement the Parent.
super(context, attrs, defStyleAttr, defStyleRes);
// Initialize Member Variables.
this.mGestureDetector = new GestureDetector(context, this);
this.mViewMap = new HashMap<>();
this.mScaleGestureDetector = new ScaleGestureDetector(context, this);
this.mScaling = false;
this.mWrapContent = false;
this.mDropOnScale = false;
// Register ourself as the OnTouchListener.
this.setOnTouchListener(this);
}
@Override
public boolean onTouch(final View v, final MotionEvent event) {
// Calculate the PointerId.
final int lPointerId = event.getPointerId(event.getActionIndex());
// Handle the TouchEvent.
this.getGestureDetector().onTouchEvent(event);
this.getScaleGestureDetector().onTouchEvent(event);
// Did the user release a pointer?
if(event.getAction() == MotionEvent.ACTION_UP) {
// Was there a View associated with this Action?
final View lView = this.getViewMap().get(lPointerId);
// Does the View exist?
if(lView != null) {
// Remove the View from the Map.
this.getViewMap().remove(lPointerId); /** TODO: Provide a Callback? */
}
}
// Consume all events for now.
return true;
}
@Override
public boolean onDown(MotionEvent e) {
// Calculate the PointerId.
final Integer lPointerId = Integer.valueOf(e.getPointerId(e.getActionIndex()));
// Fetch the View.
final View lView = this.getViewFor(Math.round(e.getRawX()), Math.round(e.getRawY()));
// Is it valid?
if(lView != null) {
// Watch the View.
this.getViewMap().put(lPointerId, lView);
// Configure the Anchor.
lView.setPivotX(0);
lView.setPivotY(0);
// Assert that we handled the event.
return true;
}
// Assert that we ignored the event.
return false;
}
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
// Are we not scaling?
if(!this.isScaling()) {
// Calculate the PointerId.
final Integer lPointerId = Integer.valueOf(e1.getPointerId(e1.getActionIndex()));
// Fetch the View.
final View lView = this.getViewMap().get(lPointerId);
// Is the scroll valid for a given View?
if(lView != null) {
// Calculate the Scaled Width and Height of the View.
final float lWidth = lView.getWidth() * lView.getScaleX();
final float lHeight = lView.getHeight() * lView.getScaleY();
// Declare the initial position.
final int[] lPosition = new int[] { (int)(e2.getX() - ((lWidth) / 2)), (int)(e2.getY() - ((lHeight) / 2)) };
// Are we wrapping content?
if(this.isWrapContent()) {
// Wrap the Position.
this.onWrapContent(lPosition, lWidth, lHeight);
}
// Update the Drag.
this.onUpdateDrag(lView, lPosition);
}
// Assert we handled the scroll.
return true;
}
// Otherwise, don't permit scrolling. Don't consume the MotionEvent.
return false;
}
/** Forces X/Y values to be coerced within the confines of the RegionView. */
private final void onWrapContent(final int[] pPosition, final float pWidth, final float pHeight) {
// Limit the parameters. (Top-Left)
pPosition[0] = Math.max(pPosition[0], 0);
pPosition[1] = Math.max(pPosition[1], 0);
// Limit the parameters. (Bottom-Right)
pPosition[0] = Math.min(pPosition[0], (int)(this.getWidth() - pWidth));
pPosition[1] = Math.min(pPosition[1], (int)(this.getHeight() - pHeight));
}
/** Updates the Drag Position of a child View within the Layout. Implicitly, we update the LayoutParams of the View. */
private final void onUpdateDrag(final View pView, final int pLeft, final int pTop) {
// Allocate some new MarginLayoutParams.
final MarginLayoutParams lMarginLayoutParams = new MarginLayoutParams(pView.getLayoutParams());
// Update the Margin.
lMarginLayoutParams.setMargins(pLeft, pTop, 0, 0);
// Refactor the MarginLayoutParams into equivalent LayoutParams for the RelativeLayout.
pView.setLayoutParams(new RelativeLayout.LayoutParams(lMarginLayoutParams));
}
@Override
public boolean onScale(ScaleGestureDetector detector) {
// Calculate the ScaleFactor.
float lScaleFactor = detector.getScaleFactor() - 1;
// Fetch the Scaled View.
final View lView = this.getViewMap().entrySet().iterator().next().getValue();
// Update the ScaleFactor.
final float lScale = this.getScale() + lScaleFactor;
// Calculate the Proposed Width and Height.
final int lWidth = Math.round(lView.getWidth() * lScale);
final int lHeight = Math.round(lView.getHeight() * lScale);
// Is the View already too large for wrap content?
if(lWidth >= this.getWidth() || lHeight >= this.getHeight()) {
// Don't update the scale.
return false;
}
// Persist this Scale for the View.
lView.setScaleX(lScale);
lView.setScaleY(lScale);
// Assign the Scale.
this.setScale(lScale);
// Compute the Position.
final int[] lPosition = new int[] { Math.round(detector.getFocusX()) - (lWidth / 2), Math.round(detector.getFocusY()) - (lHeight / 2) };
// Are we wrapping the Position?
if(this.isWrapContent()) {
// Wrap the Position.
this.onWrapContent(lPosition, lWidth, lHeight);
}
// Update the Drag.
this.onUpdateDrag(lView, lPosition);
// Assert that we handled the scale.
return true;
}
/** Update the Drag. */
private final void onUpdateDrag(final View pView, final int[] pPosition) {
// Call the sub-implementation.
this.onUpdateDrag(pView, pPosition[0], pPosition[1]);
}
@Override
public boolean onScaleBegin(ScaleGestureDetector detector) {
// Is the user not dragging at all?
if(this.getViewMap().size() == 1) {
// Fetch the View.
final View lView = this.getViewMap().entrySet().iterator().next().getValue();
// Initialize the Scale.
this.setScale(lView.getScaleX());
// Assert that we've started scaling.
this.setScaling(true);
// Inform the callback.
return true;
}
// Otherwise, don't allow scaling.
return false;
}
@Override
public void onScaleEnd(ScaleGestureDetector detector) {
// Were we scaling?
if(this.isScaling()) {
// Assert that we've stopped scaling.
this.setScaling(false);
// Reset the Scale.
this.setScale(Float.NaN);
// Should we stop dragging now that we've finished scaling?
if(this.isDropOnScale()) {
// Clear the ViewMap.
this.getViewMap().clear();
}
}
}
/** Returns the View colliding with the given co-ordinates. */
private final View getViewFor(final int pX, final int pY) {
// Declare the LocationBuffer.
final int[] lLocationBuffer = new int[2];
// Iterate the Views.
for(int i = 0; i < this.getChildCount(); i++) {
// Fetch the child View.
final View lView = this.getChildAt(i);
// Fetch its absolute position.
lView.getLocationOnScreen(lLocationBuffer);
// Determine if the MotionEvent collides with the View.
if(pX > lLocationBuffer[0] && pY > lLocationBuffer[1] && (pX < lLocationBuffer[0] + (lView.getWidth() * lView.getScaleX())) && (pY < lLocationBuffer[1] + (lView.getHeight() * lView.getScaleY()))) {
// Return the View.
return lView;
}
}
// We couldn't find a View.
return null;
}
/* Unused Overrides. */
@Override public void onShowPress(MotionEvent e) { }
@Override public boolean onSingleTapUp(MotionEvent e) {
return false;
}
@Override public void onLongPress(MotionEvent e) { }
@Override public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { return false; }
/* Getters and Setters. */
private final GestureDetector getGestureDetector() {
return this.mGestureDetector;
}
private final ScaleGestureDetector getScaleGestureDetector() {
return this.mScaleGestureDetector;
}
private final Map<Integer, View> getViewMap() {
return this.mViewMap;
}
private final void setScaling(final boolean pIsScaling) {
this.mScaling = pIsScaling;
}
private final boolean isScaling() {
return this.mScaling;
}
private final void setScale(final float pScale) {
this.mScale = pScale;
}
private final float getScale() {
return this.mScale;
}
/** Defines whether we coerce the drag and zoom of child Views within the confines of the Layout. */
public final void setWrapContent(final boolean pIsWrapContent) {
this.mWrapContent = pIsWrapContent;
}
public final boolean isWrapContent() {
return this.mWrapContent;
}
/** Defines whether a drag operation is considered 'finished' once the user finishes scaling a view. */
public final void setDropOnScale(final boolean pIsDropOnScale) {
this.mDropOnScale = pIsDropOnScale;
}
public final boolean isDropOnScale() {
return this.mDropOnScale;
}
}
Hier zeige ich einen Anwendungsbeispiel:
package com.zonal.regionview;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.AnalogClock;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Allocate a RegionView.
final RegionView lRegionView = new RegionView(this);
// Add some example items to drag.
lRegionView.addView(new AnalogClock(this));
lRegionView.addView(new AnalogClock(this));
lRegionView.addView(new AnalogClock(this));
// Assert that we only want to drag Views within the confines of the RegionView.
lRegionView.setWrapContent(true);
// Assert that after we've finished scaling a View, we want to stop being able to drag it until a new drag is started.
lRegionView.setDropOnScale(true);
// Look at the RegionView.
this.setContentView(lRegionView);
}
}