/*
* Zoom in/out. Translate the viewing window such that the place under the mouse pointer is a fixed point. If p is null, zoom around the center of
* the viewport.
*/
void zoom(double f, Point p) {
double ex = modelBounds.getWidth() * f;
double ey = modelBounds.getHeight() * f;
modelBounds.expandBy(ex / 2, ey / 2);
if (p != null) {
// Note: Graphics Y coordinates increase down the screen, hence the opposite signs.
double tx = ex * -((p.getX() / this.width) - 0.5);
double ty = ey * +((p.getY() / this.height) - 0.5);
modelBounds.translate(tx, ty);
}
// update the display
drawLevel = DRAW_PARTIAL;
}
public void mouseDragged(MouseEvent e) {
Point c = e.getPoint();
if (startDrag == null) {
startDrag = c;
dragX = c.x;
dragY = c.y;
}
double dx = dragX - c.x;
double dy = c.y - dragY;
if (ctrlPressed || mouseButton == RIGHT) {
zoom(dy * 0.01, startDrag);
} else {
double tx = modelBounds.getWidth() * dx / getWidth();
double ty = modelBounds.getHeight() * dy / getHeight();
modelBounds.translate(tx, ty);
}
dragX = c.x;
dragY = c.y;
drawLevel = DRAW_PARTIAL;
}