Merge pull request #2060 from fontforge/curve_point_tangential_adjust…

…ment_1

Add experimental support for fine point adjustment.

fontforge/views.h

@@ -1018,6 +1018,7 @@ extern Undoes *CVPreserveMaybeState(CharView *cv, int isTState );
 extern void CVRestoreTOriginalState(CharView *cv);
 extern void CVUndoCleanup(CharView *cv);
 
+extern void AdjustControls(SplinePoint *sp);
 extern void CVAdjustPoint(CharView *cv, SplinePoint *sp);
 extern void CVMergeSplineSets(CharView *cv, SplinePoint *active, SplineSet *activess,
 	SplinePoint *merge, SplineSet *mergess);

fontforgeexe/cvaddpoints.c

@@ -577,7 +577,7 @@ return;			/* We clicked on the active point, that's a no-op */
 	cv->p.constrain = sp->me;
 }
 
-static void AdjustControls(SplinePoint *sp) {
+void AdjustControls(SplinePoint *sp) {
     if ( sp->next!=NULL ) {
 	SplineCharDefaultNextCP(sp);	/* also fixes up tangents */
 	SplineCharDefaultPrevCP(sp->next->to);

fontforgeexe/cvpointer.c

@@ -1405,6 +1405,44 @@ static void touchControlPointsVisitor ( void* key,
     SPTouchControl( sp, which, (int)(intptr_t)udata );
 }
 
+#ifndef MAX
+#define MAX(x,y)   (((x) > (y)) ? (x) : (y))
+#endif
+#ifndef MIN
+#define MIN(x,y)   (((x) < (y)) ? (x) : (y))
+#endif
+
+BasePoint nearest_point_on_line_segment(BasePoint p1, BasePoint p2, BasePoint p3) {
+	double x_diff = p2.x - p1.x;
+	double y_diff = p2.y - p1.y;
+	double slope_1 = (p2.y - p1.y) / (p2.x - p1.x);
+	double inverse_slope_1 = (p2.x - p1.x) / (p2.y - p1.y);
+	BasePoint output_1;
+	output_1.x = 0;
+	output_1.y = 0;
+	// Accuracy may be important, so we try to use the longer dimension.
+	if (x_diff == 0) {
+		// The line is vertical.
+		output_1.x = p1.x;
+		output_1.y = p3.y;
+	} else if (y_diff == 0) {
+		// The line is horizontal.
+		output_1.x = p3.x;
+		output_1.y = p1.y;
+	} else {
+		output_1.x = (p3.x/slope_1 + slope_1*p1.x + p3.y - p1.y)/(slope_1 + 1/slope_1);
+		output_1.y = (p3.y/inverse_slope_1 + inverse_slope_1*p1.y + p3.x - p1.x)/(inverse_slope_1 + 1/inverse_slope_1);
+	}
+	// We are using the segment between p1 and p2, not the line through them, so we must crop.
+	double min_x = MIN(p1.x, p2.x), max_x = MAX(p1.x, p2.x), min_y = MIN(p1.y, p2.y), max_y = MAX(p1.y, p2.y);
+	if (output_1.x < min_x) output_1.x = min_x;
+	if (output_1.x > max_x) output_1.x = max_x;
+	if (output_1.y < min_y) output_1.y = min_y;
+	if (output_1.y > max_y) output_1.y = max_y;
+	// Note that it is not necessary to conform these points to the line since the corners of the box are on the line.
+	return output_1;
+}
+
 int CVMouseMovePointer(CharView *cv, GEvent *event) {
     extern float arrowAmount;
     int needsupdate = false;
@@ -1518,12 +1556,43 @@ return( false );
     {
 	if ( !cv->recentchange )
 	    CVPreserveState(&cv->b);
+
+	BasePoint tmpp1;
+	BasePoint tmpp2;
+	tmpp1.x = cv->info.x;
+	tmpp1.y = cv->info.y;
+	tmpp2.x = cv->info.x;
+	tmpp2.y = cv->info.y;
+	BasePoint cachecp1 = (cv->p.sp ? cv->p.sp->prevcp : (BasePoint){0, 0});
+	BasePoint cachecp2 = (cv->p.sp ? cv->p.sp->nextcp : (BasePoint){0, 0});
+	double xadj = cv->info.x-cv->last_c.x;
+	double yadj = cv->info.y-cv->last_c.y;
+	touch_control_points = true;
+	// The modifier is wrong.
+	if (cv->p.anysel && cv->p.sp && event->u.mouse.state & ksm_control) {
+		// Identify the individual point clicked. Find its control points. Move the selected point on a line between those control points.
+		tmpp1 = nearest_point_on_line_segment((BasePoint){cv->p.sp->prevcp.x,cv->p.sp->prevcp.y}, \
+			(BasePoint){cv->p.sp->nextcp.x,cv->p.sp->nextcp.y}, (BasePoint){cv->info.x, cv->info.y});
+		// We also need to rebase the original point onto that line segment so that the movement is exactly along the line even if the original click is not.
+		tmpp2 = nearest_point_on_line_segment((BasePoint){cv->p.sp->prevcp.x,cv->p.sp->prevcp.y}, \
+			(BasePoint){cv->p.sp->nextcp.x,cv->p.sp->nextcp.y}, (BasePoint){cv->last_c.x, cv->last_c.y});
+		xadj = tmpp1.x-tmpp2.x;
+		yadj = tmpp1.y-tmpp2.y;
+		touch_control_points = false; // We will need to move the control points back (but only for the point dragged).
+	}
 
 	did_a_merge = CVMoveSelection(cv,
-		cv->info.x-cv->last_c.x,cv->info.y-cv->last_c.y,
+		xadj,yadj,
 		event->u.mouse.state);
+	// Rather than create a new set of functions for moving points without their control points, we instead just restore them if we did not want them moved.
+	if (cv->p.sp && touch_control_points == false) {
+		cv->p.sp->prevcp = cachecp1;
+		cv->p.sp->nextcp = cachecp2;
+		touch_control_points = true;
+    		AdjustControls(cv->p.sp);
+	}
 	needsupdate = true;
-	touch_control_points = true;
+
     }