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Modify NestedScrollableHost to suit our need

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Now manages nested child scrolling when the orientation isn't perpendicular
This commit is contained in:
Ebrahim Byagowi 2020-04-15 17:23:24 +04:30
parent 6f74af7592
commit 7bdacf8fde
1 changed files with 22 additions and 44 deletions
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66
app/src/main/java/de/danoeh/antennapod/view/NestedScrollableHost.java
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@ -14,6 +14,7 @@
* limitations under the License.
*
* Source: https://github.com/android/views-widgets-samples/blob/87e58d1/ViewPager2/app/src/main/java/androidx/viewpager2/integration/testapp/NestedScrollableHost.kt
* And modified for our need
*/
package de.danoeh.antennapod.view;
@ -23,6 +24,7 @@ import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewParent;
import android.widget.FrameLayout;
import androidx.annotation.NonNull;
@ -30,6 +32,7 @@ import androidx.annotation.Nullable;
import androidx.viewpager2.widget.ViewPager2;
import static androidx.viewpager2.widget.ViewPager2.ORIENTATION_HORIZONTAL;
import static androidx.viewpager2.widget.ViewPager2.ORIENTATION_VERTICAL;
/**
* Layout to wrap a scrollable component inside a ViewPager2. Provided as a solution to the problem
@ -37,7 +40,7 @@ import static androidx.viewpager2.widget.ViewPager2.ORIENTATION_HORIZONTAL;
* ViewPager2. The scrollable element needs to be the immediate and only child of this host layout.
*
* <p>This solution has limitations when using multiple levels of nested scrollable elements
* (e.g. a horizontal RecyclerView in a vertical RecyclerView in a horizontal ViewPager2).</p>
* (e.g. a horizontal RecyclerView in a vertical RecyclerView in a horizontal ViewPager2).
*/
class NestedScrollableHost extends FrameLayout {
@ -63,47 +66,19 @@ class NestedScrollableHost extends FrameLayout {
return v == null ? null : (ViewPager2) v;
}
private View getChild() {
return getChildCount() > 0 ? getChildAt(0) : null;
}
private boolean canChildScroll(int orientation, float delta) {
int direction = (int) -Math.copySign(1, delta);
View child = getChild();
if (child == null) {
return false;
}
switch (orientation) {
case 0:
return child.canScrollHorizontally(direction);
case 1:
return child.canScrollVertically(direction);
default:
return false;
}
}
public boolean onInterceptTouchEvent(MotionEvent e) {
handleInterceptTouchEvent(e);
return super.onInterceptTouchEvent(e);
}
private void handleInterceptTouchEvent(MotionEvent e) {
ViewPager2 parentViewPager = getParentViewPager();
if (parentViewPager == null) {
return;
return super.onInterceptTouchEvent(e);
}
int orientation = parentViewPager.getOrientation();
// Early return if child can't scroll in same direction as parent
if (!canChildScroll(orientation, -1f) && !canChildScroll(orientation, 1f)) {
return;
}
ViewParent parent = getParent();
int orientation = parentViewPager.getOrientation();
if (e.getAction() == MotionEvent.ACTION_DOWN) {
initialX = e.getX();
initialY = e.getY();
getParent().requestDisallowInterceptTouchEvent(true);
parent.requestDisallowInterceptTouchEvent(true);
} else if (e.getAction() == MotionEvent.ACTION_MOVE) {
int dx = (int) (e.getX() - initialX);
int dy = (int) (e.getY() - initialY);
@ -112,22 +87,25 @@ class NestedScrollableHost extends FrameLayout {
// assuming ViewPager2 touch-slop is 2x touch-slop of child
float scaledDx = Math.abs(dx) * (isVpHorizontal ? .5f : 1f);
float scaledDy = Math.abs(dy) * (isVpHorizontal ? 1f : .5f);
if (scaledDx > touchSlop || scaledDy > touchSlop) {
int value = isVpHorizontal ? dy : dx;
if (isVpHorizontal == (scaledDy > scaledDx)) {
// Gesture is perpendicular, allow all parents to intercept
getParent().requestDisallowInterceptTouchEvent(false);
// Gesture is perpendicular
orientation = orientation == ORIENTATION_VERTICAL
? ORIENTATION_HORIZONTAL : ORIENTATION_VERTICAL;
value = isVpHorizontal ? dy : dx;
}
int direction = (int) -Math.copySign(1, value);
View child = getChildAt(0);
if (orientation == ORIENTATION_HORIZONTAL) {
parent.requestDisallowInterceptTouchEvent(child.canScrollHorizontally(direction));
} else {
// Gesture is parallel, query child if movement in that direction is possible
if (canChildScroll(orientation, isVpHorizontal ? dx : dy)) {
// Child can scroll, disallow all parents to intercept
getParent().requestDisallowInterceptTouchEvent(true);
} else {
// Child cannot scroll, allow all parents to intercept
getParent().requestDisallowInterceptTouchEvent(false);
}
parent.requestDisallowInterceptTouchEvent(child.canScrollVertically(direction));
}
}
}
return super.onInterceptTouchEvent(e);
}
}