From 8b5ae001e555cfa8fc9c747b96539cfaff643ae8 Mon Sep 17 00:00:00 2001
From: Greg King <gregdk@users.sf.net>
Date: Fri, 5 Jun 2020 13:37:20 -0400
Subject: [PATCH] Refactored the TGI demo.

Cleared the screen at the beginning of each demo instead of at the end.  Setting the colors before clearing makes it more reliable and consistent across platforms.
---
 samples/tgidemo.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/samples/tgidemo.c b/samples/tgidemo.c
index de743314e..93e91899b 100644
--- a/samples/tgidemo.c
+++ b/samples/tgidemo.c
@@ -38,8 +38,9 @@ static unsigned AspectRatio;
 static void CheckError (const char* S)
 {
     unsigned char Error = tgi_geterror ();
+
     if (Error != TGI_ERR_OK) {
-        printf ("%s: %d\n", S, Error);
+        printf ("%s: %u\n", S, Error);
         if (doesclrscrafterexit ()) {
             cgetc ();
         }
@@ -74,19 +75,19 @@ static void DoCircles (void)
     unsigned Y = MaxY / 2;
 
     tgi_setpalette (Palette);
+    tgi_setcolor (COLOR_FORE);
+    tgi_clear ();
+    tgi_line (0, 0, MaxX, MaxY);
+    tgi_line (0, MaxY, MaxX, 0);
     while (!kbhit ()) {
-        tgi_setcolor (COLOR_FORE);
-        tgi_line (0, 0, MaxX, MaxY);
-        tgi_line (0, MaxY, MaxX, 0);
+        Color = (Color == COLOR_FORE) ? COLOR_BACK : COLOR_FORE;
         tgi_setcolor (Color);
         for (I = 10; I < 240; I += 10) {
             tgi_ellipse (X, Y, I, tgi_imulround (I, AspectRatio));
         }
-        Color = Color == COLOR_FORE ? COLOR_BACK : COLOR_FORE;
     }
 
     cgetc ();
-    tgi_clear ();
 }
 
 
@@ -95,19 +96,19 @@ static void DoCheckerboard (void)
 {
     static const unsigned char Palette[2] = { TGI_COLOR_WHITE, TGI_COLOR_BLACK };
     unsigned X, Y;
-    unsigned char Color;
+    unsigned char Color = COLOR_BACK;
 
     tgi_setpalette (Palette);
-    Color = COLOR_BACK;
+    tgi_clear ();
+
     while (1) {
         for (Y = 0; Y <= MaxY; Y += 10) {
             for (X = 0; X <= MaxX; X += 10) {
+                Color = (Color == COLOR_FORE) ? COLOR_BACK : COLOR_FORE;
                 tgi_setcolor (Color);
                 tgi_bar (X, Y, X+9, Y+9);
-                Color = Color == COLOR_FORE ? COLOR_BACK : COLOR_FORE;
                 if (kbhit ()) {
                     cgetc ();
-                    tgi_clear ();
                     return;
                 }
             }
@@ -129,6 +130,7 @@ static void DoDiagram (void)
 
     tgi_setpalette (Palette);
     tgi_setcolor (COLOR_FORE);
+    tgi_clear ();
 
     /* Determine zero and aplitude */
     YOrigin = MaxY / 2;
@@ -158,7 +160,6 @@ static void DoDiagram (void)
     }
 
     cgetc ();
-    tgi_clear ();
 }
 
 
@@ -170,6 +171,7 @@ static void DoLines (void)
 
     tgi_setpalette (Palette);
     tgi_setcolor (COLOR_FORE);
+    tgi_clear ();
 
     for (X = 0; X <= MaxY; X += 10) {
         tgi_line (0, 0, MaxY, X);
@@ -179,7 +181,6 @@ static void DoLines (void)
     }
 
     cgetc ();
-    tgi_clear ();
 }
 
 
@@ -203,7 +204,6 @@ int main (void)
 
     tgi_init ();
     CheckError ("tgi_init");
-    tgi_clear ();
 
     /* Get stuff from the driver */
     MaxX = tgi_getmaxx ();