Kandinsky: KDDrawingArea uses an origin and a clipping rect

Change-Id: Iee99bc0ce12f1c2f675f7ccb6edab579b62eb77c

escher/include/escher/view.h

@@ -59,7 +59,7 @@ protected:
 private:
   void redraw(KDRect rect);
   KDPoint absoluteOrigin() const;
-  KDRect absoluteDrawingArea() const;
+  KDRect absoluteVisibleFrame() const;
 
   bool m_needsRedraw;
   //TODO: We may want a dynamic size at some point

escher/src/view.cpp

@@ -47,7 +47,13 @@ void View::redraw(KDRect rect) {
   }
 
   // First, let's draw our own content by calling drawRect
-  KDSetDrawingArea(absoluteDrawingArea());
+  KDPoint absOrigin = absoluteOrigin();
+  KDRect absRect = KDRectTranslate(rect, absOrigin);
+
+  KDRect absClippingRect = KDRectIntersection(absoluteVisibleFrame(), absRect);
+
+  KDSetDrawingArea(absOrigin, absoluteVisibleFrame());
+
   this->drawRect(rect);
 
   // Then, let's recursively draw our children over ourself
@@ -142,12 +148,12 @@ KDPoint View::absoluteOrigin() const {
   }
 }
 
-KDRect View::absoluteDrawingArea() const {
+KDRect View::absoluteVisibleFrame() const {
   if (m_superview == nullptr) {
     assert(this == (View *)window());
     return m_frame;
   } else {
-    KDRect parentDrawingArea = m_superview->absoluteDrawingArea();
+    KDRect parentDrawingArea = m_superview->absoluteVisibleFrame();
 
     KDRect absoluteFrame = m_frame;
     absoluteFrame.origin = absoluteOrigin();

kandinsky/include/kandinsky/drawing_area.h

@@ -7,6 +7,6 @@
  * When you set a drawing area (using absolute coordinates), two things happen:
  *  - No drawing will ever happen outside of the specified rect
  *  - All coordinates will then be interpreted as relative to the rect origin */
-void KDSetDrawingArea(KDRect rect);
+void KDSetDrawingArea(KDPoint origin, KDRect clippingRect);
 
 #endif

kandinsky/include/kandinsky/rect.h

@@ -27,6 +27,9 @@ extern KDRect KDRectZero;
 bool KDRectIntersect(KDRect r1, KDRect r2);
 KDRect KDRectIntersection(KDRect r1, KDRect r2);
 
+bool KDRectContains(KDRect r, KDPoint p);
+KDRect KDRectTranslate(KDRect r, KDPoint p);
+
 void KDFillRect(KDRect rect, KDColor color);
 void KDDrawRect(KDRect rect, KDColor color);
 

kandinsky/src/drawing_area.c

@@ -1,13 +1,19 @@
 #include <kandinsky/drawing_area.h>
 #include <ion.h>
 
-KDRect KDDrawingArea = {
+KDPoint KDDrawingAreaOrigin = {
+  .x = 0,
+  .y = 0
+};
+
+KDRect KDDrawingAreaClippingRect = {
   .x = 0,
   .y = 0,
   .width = ION_SCREEN_WIDTH,
   .height = ION_SCREEN_HEIGHT
 };
 
-void KDSetDrawingArea(KDRect rect) {
-  KDDrawingArea = rect;
+void KDSetDrawingArea(KDPoint origin, KDRect clippingRect) {
+  KDDrawingAreaOrigin = origin;
+  KDDrawingAreaClippingRect = clippingRect;
 }

kandinsky/src/pixel.c

@@ -1,11 +1,12 @@
 #include <kandinsky/pixel.h>
+#include <kandinsky/rect.h>
 #include <assert.h>
 #include <ion.h>
 #include "private/drawing_area.h"
 
 void KDSetPixel(KDPoint p, KDColor c) {
-  if (p.x >= 0 && p.x < KDDrawingArea.width &&
-      p.y >= 0 && p.y < KDDrawingArea.height) {
-    ion_set_pixel(p.x+KDDrawingArea.x, p.y+KDDrawingArea.y, c);
+  KDPoint absolutePoint = KDPointTranslate(p, KDDrawingAreaOrigin);
+  if (KDRectContains(KDDrawingAreaClippingRect, absolutePoint)) {
+    ion_set_pixel(absolutePoint.x, absolutePoint.y, c);
   }
 }

kandinsky/src/private/drawing_area.h

@@ -1,8 +1,10 @@
 #ifndef KANDINSKY_PRIVATE_DRAWING_AREA
 #define KANDINSKY_PRIVATE_DRAWING_AREA 1
 
+#include <kandinsky/types.h>
 #include <kandinsky/rect.h>
 
-extern KDRect KDDrawingArea;
+extern KDPoint KDDrawingAreaOrigin;
+extern KDRect KDDrawingAreaClippingRect;
 
 #endif

kandinsky/src/rect.c

@@ -42,13 +42,23 @@ KDRect KDRectIntersection(KDRect r1, KDRect r2) {
     return intersection;
 }
 
-void KDFillRect(KDRect rect, KDColor color) {
-  KDRect rectToBeFilled = {
-    .x = rect.x + KDDrawingArea.x,
-    .y = rect.y + KDDrawingArea.y,
-    .width = min(rect.width, KDDrawingArea.width),
-    .height = min(rect.height, KDDrawingArea.height)
+bool KDRectContains(KDRect r, KDPoint p) {
+  return (p.x >= r.x && p.x < (r.x+r.width) && p.y >= r.y && p.y < (r.y+r.height));
+}
+
+KDRect KDRectTranslate(KDRect r, KDPoint p) {
+  return (KDRect){
+    .origin = KDPointTranslate(r.origin, p),
+    .size = r.size
   };
+}
+
+void KDFillRect(KDRect rect, KDColor color) {
+  KDRect absolutRect = rect;
+  absolutRect.origin = KDPointTranslate(absolutRect.origin, KDDrawingAreaOrigin);
+
+  KDRect rectToBeFilled = KDRectIntersection(absolutRect, KDDrawingAreaClippingRect);
+
   ion_fill_rect(rectToBeFilled.x, rectToBeFilled.y,
       rectToBeFilled.width, rectToBeFilled.height,
       color);