Clip Painter operations to the screen rect.

Widgets/Painter.cpp

@@ -4,6 +4,7 @@
 #include "Font.h"
 #include "Window.h"
 #include <AK/Assertions.h>
+#include <AK/StdLib.h>
 #include <SDL.h>
 
 Painter::Painter(Widget& widget)
@@ -17,6 +18,9 @@ Painter::Painter(Widget& widget)
         m_translation.setX(widget.x());
         m_translation.setY(widget.y());
     }
+
+    m_clipRect.setWidth(AbstractScreen::the().width());
+    m_clipRect.setHeight(AbstractScreen::the().height());
 }
 
 Painter::~Painter()
@@ -36,9 +40,9 @@ void Painter::fillRect(const Rect& rect, Color color)
     Rect r = rect;
     r.moveBy(m_translation);
 
-    for (int y = r.top(); y < r.bottom(); ++y) {
+    for (int y = max(r.top(), m_clipRect.top()); y < min(r.bottom(), m_clipRect.bottom()); ++y) {
         dword* bits = scanline(y);
-        for (int x = r.left(); x < r.right(); ++x) {
+        for (int x = max(r.left(), m_clipRect.left()); x < min(r.right(), m_clipRect.right()); ++x) {
             bits[x] = color.value();
         }
     }
@@ -49,15 +53,17 @@ void Painter::drawRect(const Rect& rect, Color color)
     Rect r = rect;
     r.moveBy(m_translation);
 
-    for (int y = r.top(); y < r.bottom(); ++y) {
+    for (int y = max(r.top(), m_clipRect.top()); y < min(r.bottom(), m_clipRect.bottom()); ++y) {
         dword* bits = scanline(y);
         if (y == r.top() || y == (r.bottom() - 1)) {
-            for (int x = r.left(); x < r.right(); ++x) {
+            for (int x = max(r.left(), m_clipRect.left()); x < min(r.right(), m_clipRect.right()); ++x) {
                 bits[x] = color.value();
             }
         } else {
-            bits[r.left()] = color.value();
+            if (r.left() >= m_clipRect.left() && r.left() < m_clipRect.right())
-            bits[r.right() - 1] = color.value();
+                bits[r.left()] = color.value();
+            if (r.right() >= m_clipRect.left() && r.right() < m_clipRect.right())
+                bits[r.right() - 1] = color.value();
         }
     }
 }
@@ -67,15 +73,17 @@ void Painter::xorRect(const Rect& rect, Color color)
     Rect r = rect;
     r.moveBy(m_translation);
 
-    for (int y = r.top(); y < r.bottom(); ++y) {
+    for (int y = max(r.top(), m_clipRect.top()); y < min(r.bottom(), m_clipRect.bottom()); ++y) {
         dword* bits = scanline(y);
         if (y == r.top() || y == (r.bottom() - 1)) {
-            for (int x = r.left(); x < r.right(); ++x) {
+            for (int x = max(r.left(), m_clipRect.left()); x < min(r.right(), m_clipRect.right()); ++x) {
                 bits[x] ^= color.value();
             }
         } else {
-            bits[r.left()] ^= color.value();
+            if (r.left() >= m_clipRect.left() && r.left() < m_clipRect.right())
-            bits[r.right() - 1] ^= color.value();
+                bits[r.left()] ^= color.value();
+            if (r.right() >= m_clipRect.left() && r.right() < m_clipRect.right())
+                bits[r.right() - 1] ^= color.value();
         }
     }
 }
@@ -86,12 +94,16 @@ void Painter::drawBitmap(const Point& p, const CBitmap& bitmap, Color color)
     point.moveBy(m_translation);
     for (unsigned row = 0; row < bitmap.height(); ++row) {
         int y = point.y() + row;
-        int x = point.x();
+        if (y < m_clipRect.top() || y >= m_clipRect.bottom())
+            break;
         dword* bits = scanline(y);
         for (unsigned j = 0; j < bitmap.width(); ++j) {
+            int x = point.x() + j;
+            if (x < m_clipRect.left() || x >= m_clipRect.right())
+                break;
             char fc = bitmap.bits()[row * bitmap.width() + j];
             if (fc == '#')
-                bits[x + j] = color.value();
+                bits[x] = color.value();
         }
     }
 }
@@ -129,6 +141,8 @@ void Painter::drawPixel(const Point& p, Color color)
 {
     auto point = p;
     point.moveBy(m_translation);
+    if (!m_clipRect.contains(point))
+        return;
     scanline(point.y())[point.x()] = color.value();
 }
 
@@ -142,10 +156,13 @@ void Painter::drawLine(const Point& p1, const Point& p2, Color color)
 
     // Special case: vertical line.
     if (point1.x() == point2.x()) {
+        const int x = point1.x();
+        if (x < m_clipRect.left() || x >= m_clipRect.right())
+            return;
         if (point1.y() > point2.y())
             std::swap(point1, point2);
-        for (int y = point1.y(); y <= point2.y(); ++y)
+        for (int y = max(point1.y(), m_clipRect.top()); y <= min(point2.y(), m_clipRect.bottom()); ++y)
-            scanline(y)[point1.x()] = color.value();
+            scanline(y)[x] = color.value();
         return;
     }
 
@@ -154,14 +171,20 @@ void Painter::drawLine(const Point& p1, const Point& p2, Color color)
 
     // Special case: horizontal line.
     if (point1.y() == point2.y()) {
-        if (point1.y() > point2.y())
+        const int y = point1.y();
+        if (y < m_clipRect.top() || y >= m_clipRect.bottom())
+            return;
+        if (point1.x() > point2.x())
             std::swap(point1, point2);
         auto* pixels = scanline(point1.y());
-        for (int x = point1.x(); x <= point2.x(); ++x)
+        for (int x = max(point1.x(), m_clipRect.left()); x <= min(point2.x(), m_clipRect.right()); ++x)
             pixels[x] = color.value();
         return;
     }
 
+    // FIXME: Implement clipping below.
+    ASSERT_NOT_REACHED();
+
     const double dx = point2.x() - point1.x();
     const double dy = point2.y() - point1.y();
     const double deltaError = fabs(dy / dx);

Widgets/Painter.h

@@ -30,4 +30,6 @@ private:
     Widget& m_widget;
     Font& m_font;
     Point m_translation;
+
+    Rect m_clipRect;
 };

Widgets/Rect.h

@@ -42,7 +42,7 @@ public:
 
     bool contains(int x, int y) const
     {
-        return x >= m_location.x() && x <= right() && y >= m_location.y() && y <= bottom();
+        return x >= m_location.x() && x < right() && y >= m_location.y() && y < bottom();
     }
 
     bool contains(const Point& point) const

Widgets/TerminalWidget.cpp

@@ -133,6 +133,9 @@ void TerminalWidget::onReceive(byte ch)
                 at(m_cursorRow, m_cursorColumn).character = ' ';
             }
             break;
+        case 27:
+            printf("TerminalWidget: got escape!\n");
+            break;
         default:
             addChar(ch);
             break;