Move win-agnostic parts of draw/drawregion to st.c

Introduces three functions to encapsulate X-specific behavior:
 * xdrawline: draws a portion of a single line (used by drawregion)
 * xbegindraw: called to prepare for drawing (will be useful for e.g.
   Wayland) and returns true if drawing should happen
 * xfinishdraw: called to finish drawing (used by draw)

Signed-off-by: Devin J. Pohly <djpohly@gmail.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/st.c b/st.c
index 01791a5..504239e 100644
--- a/st.c
+++ b/st.c
@@ -166,6 +166,8 @@ static int32_t tdefcolor(int *, int *, int);
 static void tdeftran(char);
 static void tstrsequence(uchar);
 
+static void drawregion(int, int, int, int);
+
 static void selscroll(int, int);
 static void selsnap(int *, int *, int);
 
@@ -2527,6 +2529,29 @@ resettitle(void)
 }
 
 void
+drawregion(int x1, int y1, int x2, int y2)
+{
+        int y;
+        for (y = y1; y < y2; y++) {
+                if (!term.dirty[y])
+                        continue;
+
+                term.dirty[y] = 0;
+                xdrawline(term.line[y], x1, y, x2);
+        }
+}
+
+void
+draw(void)
+{
+        if (!xstartdraw())
+                return;
+        drawregion(0, 0, term.col, term.row);
+        xdrawcursor();
+        xfinishdraw();
+}
+
+void
 redraw(void)
 {
         tfulldirt();