added DrawBuf,drawLine() - issue #64 - based on code from Ted Bullen; OpenGL version of drawLine still needs optimization to avoid drawing by-pixel

examples/example1/src/example1.d

@@ -843,14 +843,20 @@ void main()
 		CanvasWidget canvas = new CanvasWidget("canvas");
 		canvas.layoutWidth(FILL_PARENT).layoutHeight(FILL_PARENT);
 		canvas.onDrawListener = delegate(CanvasWidget canvas, DrawBuf buf, Rect rc) {
+			buf.fill(0xFFFFFF);
 			int x = rc.left;
 			int y = rc.top;
 			buf.fillRect(Rect(x+20, y+20, x+150, y+200), 0x80FF80);
 			buf.fillRect(Rect(x+90, y+80, x+250, y+250), 0x80FF80FF);
 			canvas.font.drawText(buf, x + 40, y + 50, "fillRect()"d, 0xC080C0);
+			buf.drawFrame(Rect(x + 400, y + 30, x + 550, y + 150), 0x204060, Rect(2,3,4,5), 0x80704020);
+			canvas.font.drawText(buf, x + 400, y + 5, "drawFrame()"d, 0x208020);
 			canvas.font.drawText(buf, x + 300, y + 100, "drawPixel()"d, 0x000080);
 			for (int i = 0; i < 80; i++)
 				buf.drawPixel(x+300 + i * 4, y+140 + i * 3 % 100, 0xFF0000 + i * 2);
+			canvas.font.drawText(buf, x + 200, y + 250, "drawLine()"d, 0x800020);
+			for (int i = 0; i < 40; i+=3)
+				buf.drawLine(Point(x+200 + i * 4, y+290), Point(x+150 + i * 7, y+420 + i * 2), 0x008000 + i * 5);
 		};
 		tabs.addTab(canvas, "TAB_CANVAS"c);
 

src/dlangui/graphics/drawbuf.d

@@ -338,6 +338,50 @@ class DrawBuf : RefCountedObject {
         }
     }
 
+	/// draw line from point p1 to p2 with specified color
+	void drawLine(Point p1, Point p2, uint colour) {
+		if (p1.x < _clipRect.left && p2.x < _clipRect.left)
+			return;
+		if (p1.y < _clipRect.top && p2.y < _clipRect.top)
+			return;
+		if (p1.x >= _clipRect.right && p2.x >= _clipRect.right)
+			return;
+		if (p1.y >= _clipRect.bottom && p2.y >= _clipRect.bottom)
+			return;
+		// from rosettacode.org
+		import std.math: abs;
+		immutable int dx = p2.x - p1.x;
+		immutable int ix = (dx > 0) - (dx < 0);
+		immutable int dx2 = abs(dx) * 2;
+		int dy = p2.y - p1.y;
+		immutable int iy = (dy > 0) - (dy < 0);
+		immutable int dy2 = abs(dy) * 2;
+		drawPixel(p1.x, p1.y, colour);
+		if (dx2 >= dy2) {
+			int error = dy2 - (dx2 / 2);
+			while (p1.x != p2.x) {
+				if (error >= 0 && (error || (ix > 0))) {
+					error -= dx2;
+					p1.y += iy;
+				}
+				error += dy2;
+				p1.x += ix;
+				drawPixel(p1.x, p1.y, colour);
+			}
+		} else {
+			int error = dx2 - (dy2 / 2);
+			while (p1.y != p2.y) {
+				if (error >= 0 && (error || (iy > 0))) {
+					error -= dy2;
+					p1.x += ix;
+				}
+				error += dx2;
+				p1.y += iy;
+				drawPixel(p1.x, p1.y, colour);
+			}
+		}
+	}
+
     /// create drawbuf with copy of current buffer with changed colors (returns this if not supported)
     DrawBuf transformColors(ref ColorTransform transform) {
         return this;