1 files changed, 64 insertions, 0 deletions

diff --git a/src/FbTk/FbDrawable.cc b/src/FbTk/FbDrawable.cc
index 061da0b..dd6e4a9 100644
--- a/src/FbTk/FbDrawable.cc
+++ b/src/FbTk/FbDrawable.cc
@@ -89,6 +89,70 @@ void FbDrawable::fillPolygon(GC gc, XPoint *points, int npoints,
                  shape, mode);
 }
 
+// x, y, width and height define a space within which we're drawing a triangle (centred)
+// scale defines number of triangles that'd fit in a space of 100 width x 100 height
+// (i.e. 200 = half size, 300 = a third). Its a bit backwards but it allows more flexibility
+void FbDrawable::drawTriangle(GC gc, FbDrawable::TriangleType type, 
+                              int x, int y, unsigned int width, unsigned int height,
+                              int scale) {
+    if (drawable() == 0 || gc == 0 || width == 0 || height == 0)
+        return;
+
+    XPoint pts[3];
+
+    if (scale < 100) scale = 100; // not bigger than the space allowed
+    else if (scale > 10000) scale = 10000; // not too small...
+
+    int arrowscale_n = scale;
+    int arrowscale_d = 100;
+    unsigned int ax = arrowscale_d * width / arrowscale_n;
+    unsigned int ay = arrowscale_d * height / arrowscale_n;
+    // if these aren't an even number, left and right arrows end up different
+    if (type == FbTk::FbDrawable::LEFT ||
+        type == FbTk::FbDrawable::RIGHT) {
+        if (( ax % 2 ) == 1) ax--;
+        if (( ay % 2 ) == 1) ay--;
+    } else {
+        if (( ax % 2 ) == 0) ax--;
+    }
+
+    switch (type) {
+    case FbTk::FbDrawable::LEFT:
+        // start at the tip
+        pts[0].x = (width / 2) - (ax / 2); pts[0].y = height / 2;
+        pts[1].x = ax; pts[1].y = -ay / 2;
+        pts[2].x = 0; pts[2].y = ay;
+        break;
+    case FbTk::FbDrawable::RIGHT:
+        pts[0].x = (width / 2) + (ax / 2); pts[0].y = height / 2;
+        pts[1].x = - ax; pts[1].y = ay / 2;
+        pts[2].x = 0; pts[2].y = - ay;
+        break;
+    case FbTk::FbDrawable::UP:
+        pts[0].x = (width / 2); pts[0].y = (height / 2) - (ay / 2)-1;
+        pts[1].x = ax / 2; pts[1].y = ay+1;
+        pts[2].x = - ax; pts[2].y = 0;
+        break;
+    case FbTk::FbDrawable::DOWN:
+        /* I tried and tried, but couldn't get the left diagonal of the down
+           arrow to be symmetrical with the right (for small widths)!
+           So we opt for this setup. It is symmetrical with larger widths */
+        pts[0].x = (width / 2) ; pts[0].y = (height / 2) + (ay / 2);
+        pts[1].x = -ax/2+1; pts[1].y = -ay;
+        pts[2].x = ax-1; pts[2].y = 0;
+        break;
+  
+    }
+
+    // re-centre on the specified points
+    pts[0].x += x;
+    pts[0].y += y;
+
+    fillPolygon(gc,
+                pts, 3, 
+                Convex, CoordModePrevious);
+}
+
 #ifdef NOT_USED
 void FbDrawable::drawPoint(GC gc, int x, int y) {
     if (drawable() == 0 || gc == 0)