Add somewhat ridiculous debug hacks for CoreGrahics drawing debugging on iOS

When the environment variable DRAW_INCREMENTALLY_FROM is set to a
number, we want TiledLibreOffice to loop, initially performing only
that number of drawing operations in AquaSalGraphics, then wait for
some seconds, and redraw. Next time perform one operation
more. Repeat.

Implemented in vcl by surrounding the entry and exit(s) of the drawing
functions in AquaSalGraphics with macros.

All this is active only for iOS and in a dbgutil build.

ios/experimental/TiledLibreOffice/TiledLibreOffice/TiledView.m

@@ -82,6 +82,20 @@ static void updateTilesPerSecond(UILabel *label)
     }
 }
 
+static int DBG_DRAW_DELAY = 10;
+int DBG_DRAW_ROUNDS = -1;
+int DBG_DRAW_COUNTER = 0;
+int DBG_DRAW_ROUNDS_MAX = INT_MAX;
+
+- (void)redraw
+{
+    DBG_DRAW_ROUNDS++;
+    DBG_DRAW_COUNTER = 0;
+    [self setNeedsDisplay];
+    if (DBG_DRAW_ROUNDS < DBG_DRAW_ROUNDS_MAX)
+        [NSTimer scheduledTimerWithTimeInterval:DBG_DRAW_DELAY target:self selector:@selector(redraw) userInfo:nil repeats:NO];
+}
+
 - (id)initWithFrame:(CGRect)frame scale:(CGFloat)scale maxZoom:(int)maxZoom
 {
     self = [super initWithFrame:frame];
@@ -93,6 +107,13 @@ static void updateTilesPerSecond(UILabel *label)
         catl.levelsOfDetailBias = catl.levelsOfDetail - 1;
 
         [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(updateTilesPerSecond) userInfo:nil repeats:YES];
+        if (getenv("DRAW_INCREMENTALLY_FROM")) {
+            DBG_DRAW_ROUNDS = atoi(getenv("DRAW_INCREMENTALLY_FROM"));
+            if (getenv("DRAW_INCREMENTALLY_DELAY") &&
+                atoi(getenv("DRAW_INCREMENTALLY_DELAY")) > 1)
+                DBG_DRAW_DELAY = atoi(getenv("DRAW_INCREMENTALLY_DELAY"));
+            [NSTimer scheduledTimerWithTimeInterval:DBG_DRAW_DELAY target:self selector:@selector(redraw) userInfo:nil repeats:NO];
+        }
     }
     return self;
 }
@@ -138,12 +159,13 @@ static bool tileMatches(const char *spec, CGRect bb)
     // as needed at the current zoom levels. I keep thinking about
     // "pixels" incorrectly.
 
-    if (!getenv("DRAW_ONLY_TILE") || tileMatches(getenv("DRAW_ONLY_TILE"), bb))
+    if (!getenv("DRAW_ONLY_TILE") || tileMatches(getenv("DRAW_ONLY_TILE"), bb)) {
+        fprintf(stderr, "+++ rendering to context %p\n", ctx);
         touch_lo_draw_tile(ctx,
                            tileSize.width, tileSize.height,
                            CGPointMake(bb.origin.x/self.scale, bb.origin.y/self.scale),
                            CGSizeMake(bb.size.width/self.scale, bb.size.height/self.scale));
-    else {
+    } else {
         CGContextSetRGBFillColor(ctx, 1, 1, 1, 1);
         CGContextFillRect(ctx, CGRectMake(0, 0, bb.size.width, bb.size.height));
     }