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Add pinch to zoom touch gestures

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This commit is contained in:
Antoine d'Aligny 2019-10-05 12:06:00 +02:00 committed by Daniel Micay
parent 1f229ad9a8
commit 0ac0102a8a
1 changed files with 57 additions and 11 deletions
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66
app/src/main/java/org/grapheneos/pdfviewer/PdfViewer.java
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@ -14,6 +14,7 @@ import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
import android.webkit.CookieManager;
import android.webkit.JavascriptInterface;
@ -254,8 +255,45 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
return false;
}
});
final ScaleGestureDetector scaleDetector = new ScaleGestureDetector(PdfViewer.this,
new ScaleGestureDetector.SimpleOnScaleGestureListener() {
// As the zoom value is discrete we listen to scaling step and not scaling ratio
float SPAN_STEP = 150;
float initialSpan;
int prevNbStep;
@Override
public boolean onScaleBegin(ScaleGestureDetector detector) {
initialSpan = detector.getCurrentSpan();
prevNbStep = 0;
return super.onScaleBegin(detector);
}
@Override
public boolean onScale(ScaleGestureDetector detector) {
float spanDiff = initialSpan - detector.getCurrentSpan();
int curNbStep = (int) (spanDiff/SPAN_STEP);
if (curNbStep != prevNbStep) {
int stepDiff = curNbStep - prevNbStep;
if (stepDiff > 0) {
for (int i = prevNbStep; i < curNbStep; i++) {
zoomOut();
}
} else {
for (int i = prevNbStep; i > curNbStep; i--) {
zoomIn();
}
}
prevNbStep = curNbStep;
}
return true;
}
});
mWebView.setOnTouchListener((view, motionEvent) -> {
detector.onTouchEvent(motionEvent);
scaleDetector.onTouchEvent(motionEvent);
return false;
});
@ -340,6 +378,22 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
startActivityForResult(intent, ACTION_OPEN_DOCUMENT_REQUEST_CODE);
}
private void zoomIn() {
if (mZoomLevel < MAX_ZOOM_LEVEL) {
mZoomLevel++;
renderPage(true);
invalidateOptionsMenu();
}
}
private void zoomOut() {
if (mZoomLevel > 0) {
mZoomLevel--;
renderPage(true);
invalidateOptionsMenu();
}
}
private static void enableDisableMenuItem(MenuItem item, boolean enable) {
if (enable) {
if (!item.isEnabled()) {
@ -482,19 +536,11 @@ public class PdfViewer extends AppCompatActivity implements LoaderManager.Loader
return super.onOptionsItemSelected(item);
case R.id.action_zoom_out:
if (mZoomLevel > 0) {
mZoomLevel--;
renderPage(true);
invalidateOptionsMenu();
}
zoomOut();
return true;
case R.id.action_zoom_in:
if (mZoomLevel < MAX_ZOOM_LEVEL) {
mZoomLevel++;
renderPage(true);
invalidateOptionsMenu();
}
zoomIn();
return true;
case R.id.action_rotate_clockwise: