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fix #128, significantly improved zoom implementation
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@mkrupczak3
mkrupczak3 committed Apr 27, 2024
1 parent d88b455 commit 88ce46e
Showing 1 changed file with 114 additions and 79 deletions.
193 changes: 114 additions & 79 deletions app/src/main/java/com/openathena/MarkableImageView.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2,13 +2,16 @@

import static com.openathena.AthenaActivity.TAG;

import android.annotation.SuppressLint;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.RectF;
import android.net.Uri;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
Expand All @@ -35,14 +38,15 @@ public class MarkableImageView extends androidx.appcompat.widget.AppCompatImageV
private long lastScaleGestureTime = 0;
private static final long SCALE_COOLDOWN_MS = 350;

private float scale = 1f; // Initial scale
private float translationX = 0f; // Initial translation
private float translationY = 0f; // Initial translation
private float screen_pixel_density = getResources().getDisplayMetrics().density;

private Matrix matrix = new Matrix();

private int activePointerId = MotionEvent.INVALID_POINTER_ID;
protected boolean isDragging = false;
protected boolean isScaling = false;

@SuppressLint("ClickableViewAccessibility")
public MarkableImageView(Context context, AttributeSet attrs) {
super(context, attrs);
if (!(context instanceof AthenaActivity)) {
Expand All @@ -51,8 +55,7 @@ public MarkableImageView(Context context, AttributeSet attrs) {
parent = (AthenaActivity) context;

DisplayMetrics metrics = new DisplayMetrics();
float screen_pixel_density = getResources().getDisplayMetrics().density;
final float clickThreshold = 15f * screen_pixel_density;
final float clickThreshold = 6f * screen_pixel_density;

scaleGestureDetector = new ScaleGestureDetector(context, new MyScaleGestureListener());
gestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
Expand Down Expand Up @@ -81,15 +84,16 @@ public boolean onDoubleTap(MotionEvent e) {
private float lastX, lastY;


@SuppressLint("ClickableViewAccessibility")
@Override
public boolean onTouch(View v, MotionEvent event) {
// Detect gestures
scaleGestureDetector.onTouchEvent(event);
gestureDetector.onTouchEvent(event);

final int action = event.getActionMasked();
int pointerId = -1;
int pointerIndex = -1;
int pointerIndex = event.getActionIndex();
int pointerId = event.getPointerId(pointerIndex);

if (isScaling) {
// Ignore taps if pinch to zoom scaling is being performed
Expand All @@ -111,28 +115,36 @@ public boolean onTouch(View v, MotionEvent event) {
break;
case MotionEvent.ACTION_MOVE:
pointerIndex = event.findPointerIndex(activePointerId);
if (pointerIndex != -1) {
if (isScaling) {
// Ignore move if pinch to zoom scaling is being performed
return true;
}
if (pointerIndex != -1 && event.getPointerCount() == 1) {
float x = event.getX(pointerIndex);
float y = event.getY(pointerIndex);
float dx = event.getX() - lastX;
float dy = event.getY() - lastY;
float dx = x - lastX;
float dy = y - lastY;
if (!isDragging) {
isDragging = Math.sqrt((dx * dx) + (dy * dy)) >= clickThreshold;
}
if (isDragging) {
// Adjust translations based on drag, accounting for scale
translationX += dx / scale;
translationY += dy / scale;

if (isDragging) {
matrix.postTranslate(event.getX() - lastX, event.getY() - lastY);
restrictTranslationToContent();

invalidate();
setImageMatrix(matrix);
}
lastX = event.getX();
lastY = event.getY();
lastX = x;
lastY = y;
}
break;
case MotionEvent.ACTION_POINTER_DOWN:
// When a new pointer is added, evaluate and possibly reset the drag start coordinates
if (event.getPointerCount() == 2) { // Start of a pinch-to-zoom gesture
int newPointerIndex = (pointerIndex == 0) ? 1 : 0;
lastX = event.getX(newPointerIndex);
lastY = event.getY(newPointerIndex);
activePointerId = event.getPointerId(newPointerIndex);
}
break;
case MotionEvent.ACTION_CANCEL: {
activePointerId = MotionEvent.INVALID_POINTER_ID;
Expand Down Expand Up @@ -177,33 +189,32 @@ private void handleTap(float x, float y) {
if (!parent.isImageLoaded || parent.imageUri == null || parent.iView == null) {
return;
}
int original_width;
int original_height;

int[] original_dimensions = parent.getImageDimensionsFromUri(parent.imageUri);
if (original_dimensions == null) {
return;
} else {
original_width = original_dimensions[0];
original_height = original_dimensions[1];
}
double render_width = yahweh.getWidth();
double render_height = yahweh.getHeight();

// Correctly adjust tap coordinates for scale and translation
float adjustedX = (x - translationX * scale) / scale;
float adjustedY = (y - translationY * scale) / scale;
int original_width = original_dimensions[0];
int original_height = original_dimensions[1];

// Get the inverse of the current matrix transformation
Matrix inversedMatrix = new Matrix();
matrix.invert(inversedMatrix);

// Transform the tap coordinates to the original image coordinates
float[] transformedCoords = { x, y };
inversedMatrix.mapPoints(transformedCoords);

// Calculate the proportion of the tap within the image dimensions
float proportionX = adjustedX / getWidth();
float proportionY = adjustedY / getHeight();
float proportionX = transformedCoords[0] / getWidth();
float proportionY = transformedCoords[1] / getHeight();

parent.set_selection_x((int) Math.round(proportionX * original_width));
parent.set_selection_y((int) Math.round(proportionY * original_height));
Log.d("X", parent.get_selection_x() + "");
Log.d("Y", parent.get_selection_y() + "");

if (parent.isImageLoaded && parent.isDEMLoaded) {
parent.calculateImage(yahweh, false); // this may cause the view to re-size due to constraint layout
parent.calculateImage(yahweh, false);
yahweh.mark(proportionX, proportionY);
}
}
Expand All @@ -230,63 +241,78 @@ public boolean onScaleBegin(ScaleGestureDetector detector) {
lastScaleGestureTime = currentTime;

isScaling = true; // Scaling begins
isDragging = false;

return true;
}
@Override
public boolean onScale(ScaleGestureDetector detector) {
long currentTime = System.currentTimeMillis();
final float SCALE_SENSITIVITY = 0.5f;
float lastScaleValue = scale;
float adjustScaleFactor = detector.getScaleFactor();

float scaleFactor = detector.getScaleFactor();
scaleFactor = 1 + SCALE_SENSITIVITY * (scaleFactor - 1);
// Get current scale
float[] matrixValues = new float[9];
matrix.getValues(matrixValues);
float currentScale = matrixValues[Matrix.MSCALE_X]; // Assumes uniform scaling

scale *= scaleFactor;
if (currentTime - lastIntentTime > INTENT_COOLDOWN_MS) {
if (parent instanceof SelectionActivity) {
final float scaleThreshold = 0.92f;
if (scale < scaleThreshold && lastScaleValue < scaleThreshold) { // Check for pinch-to-zoom-out gesture
Intent intent = new Intent(parent, MainActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NEW_TASK);
parent.startActivity(intent);
lastIntentTime = currentTime;
}
}
}
scale = Math.max(0.90f, Math.min(scale, 5.0f)); // Constrain scale between 0.9 and 5.0
lastScaleGestureTime = currentTime;
// Calculate the scale factor to apply considering the constraints
float targetScale = currentScale * adjustScaleFactor;
float clampedScaleFactor = clamp(targetScale, 0.90f, 5.0f) / currentScale;

matrix.postScale(clampedScaleFactor, clampedScaleFactor, detector.getFocusX(), detector.getFocusY());
restrictTranslationToContent();
invalidate();
return super.onScale(detector);
setImageMatrix(matrix);

return true;
}
@Override
public void onScaleEnd(ScaleGestureDetector detector) {
long currentTime = System.currentTimeMillis();
lastScaleGestureTime = currentTime;

isScaling = false; // Scaling ends
isDragging = false;
super.onScaleEnd(detector);
}
}

private void restrictTranslationToContent() {
// Get drawable dimensions
float drawableWidth = getDrawable().getIntrinsicWidth();
float drawableHeight = getDrawable().getIntrinsicHeight();

// Create a matrix values array
float[] values = new float[9];
matrix.getValues(values);

// Extract the scale and translation from the matrix
float scale = values[Matrix.MSCALE_X]; // Assuming uniform scale in X and Y
float transX = values[Matrix.MTRANS_X];
float transY = values[Matrix.MTRANS_Y];

float minTransX; float maxTransX;
float minTransY; float maxTransY;
if (scale > 1.0f) { // constrain view window to be within content when zoomed
// Calculate the boundaries for translation
minTransX = (getWidth() / scale) - getWidth();
maxTransX = 0.0f;
minTransY = (getHeight() / scale) - getHeight();
maxTransY = 0.0f;
} else { // constrain content to center of view window when un-zoomed
minTransX = ((getWidth() / scale) - getWidth()) / 2.0f;

if (scale > 1.0f) {
minTransX = getWidth() - getWidth() * scale; // Maximum leftward translation
minTransY = getHeight() - getHeight() * scale; // Maximum upward translation
maxTransX = 0; // Image cannot translate right beyond original position
maxTransY = 0; // Image cannot translate down beyond original position
} else {
minTransX = (getWidth() - getWidth() * scale) / 2.0f;
maxTransX = minTransX;
minTransY = ((getHeight() / scale) - getHeight()) / 2.0f;
minTransY = (getHeight() - getHeight() * scale) / 2.0f;
maxTransY = minTransY;
}
// Apply boundaries
translationX = clamp(translationX, minTransX, maxTransX);
translationY = clamp(translationY, minTransY, maxTransY);
// Clamp current translations
float clampedTransX = clamp(transX, minTransX, maxTransX);
float clampedTransY = clamp(transY, minTransY, maxTransY);

// Calculate the delta to correct any out-of-bound positions
float deltaX = clampedTransX - transX;
float deltaY = clampedTransY - transY;

// Apply translation to the matrix
matrix.postTranslate(deltaX, deltaY);
}

// Clamp function to restrict a value between a minimum and a maximum
Expand All @@ -313,9 +339,8 @@ public void restoreMarker(int selection_x, int selection_y) {

public void reset() {
this.mark(0.5d, 0.5d);
scale = 1.0f;
translationX = 0.0f;
translationY = 0.0f;
matrix.reset();
setImageMatrix(matrix);
}

/**
Expand All @@ -329,11 +354,19 @@ public void mark(double x, double y) {
}

private void setMarkerPosition(float x, float y) {
float x_prop; float y_prop;
float x_prop, y_prop;
if (getWidth() > 0 && getHeight() > 0) {
// Adjust the marker position to account for the current zoom and pan
x_prop = (x - translationX) / (getWidth() * scale);
y_prop = (y - translationY) / (getHeight() * scale);
// Get the inverse of the current matrix transformation
Matrix inversedMatrix = new Matrix();
matrix.invert(inversedMatrix);

// Transform the coordinates to the original image coordinates
float[] transformedCoords = {x, y};
inversedMatrix.mapPoints(transformedCoords);

// Calculate the marker position as a proportion of the view dimensions
x_prop = transformedCoords[0] / getWidth();
y_prop = transformedCoords[1] / getHeight();
} else {
Log.e(TAG, "Error: width or height was zero at time of marking");
return;
Expand All @@ -343,15 +376,16 @@ private void setMarkerPosition(float x, float y) {

@Override
protected void onDraw(Canvas canvas) {

// Save the current canvas matrix
// Save the current canvas state
canvas.save();

// Apply zoom and translation
canvas.scale(scale, scale);
canvas.translate(translationX, translationY);
// Apply the combined transformations from the matrix
canvas.concat(matrix);

// Draw the image
super.onDraw(canvas);

// Draw the marker if it exists
if (theMarker != null) {
float length = Math.max(getWidth() / 48, getHeight() / 48);
float gap = length / 1.5f;
Expand All @@ -372,13 +406,14 @@ protected void onDraw(Canvas canvas) {
canvas.drawLine(actualX, actualY - length - gap, actualX, actualY - gap, paint);
canvas.drawLine(actualX, actualY + gap, actualX, actualY + length + gap, paint);
} else {
// If no marker exists and the image is loaded, create a default marker at the center
if (parent.isImageLoaded) {
theMarker = new Marker(0.5d, 0.5d);
invalidate();
}
}

// Restore the canvas matrix
// Restore the canvas state
canvas.restore();
}

Expand Down

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