hardcoresushi/libpdfviewer
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support non-step-based zooming

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This commit is contained in:
Daniel Micay 2020-04-04 12:21:25 -04:00
parent f780734c9c
commit c6a90066a2
1 changed files with 11 additions and 12 deletions
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23
app/src/main/java/org/grapheneos/pdfviewer/GestureHelper.java
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@ -33,10 +33,9 @@ class GestureHelper {
final ScaleGestureDetector scaleDetector = new ScaleGestureDetector(context,
new ScaleGestureDetector.SimpleOnScaleGestureListener() {
// As the zoom value is discrete we listen to scaling step and not scaling ratio
float SPAN_STEP = 150;
float SPAN_RATIO = 600;
float initialSpan;
int prevNbStep;
float prevNbStep;
@Override
public boolean onScaleBegin(ScaleGestureDetector detector) {
@ -48,16 +47,16 @@ class GestureHelper {
@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) {
listener.onZoomOut(stepDiff * 0.25f);
} else {
listener.onZoomIn(Math.abs(stepDiff * 0.25f));
}
prevNbStep = curNbStep;
float curNbStep = spanDiff / SPAN_RATIO;
float stepDiff = curNbStep - prevNbStep;
if (stepDiff > 0) {
listener.onZoomOut(stepDiff);
} else {
listener.onZoomIn(Math.abs(stepDiff));
}
prevNbStep = curNbStep;
return true;
}