Add possibility to show tile numbers and render just one tile

Useful for debugging. Also, make the tile border drawing
optional. These three debugging features are governed by environment
variales (set in Xcode before running with Alt+Product>Run...)
DRAW_ONLY_TILE, DRAW_TILE_BORDERS and DRAW_TILE_NUMBERS.

Change-Id: I81f952284676eafe5d204c819658e0225aabdb1c

ios/experimental/TiledLibreOffice/TiledLibreOffice/TiledView.m

@@ -6,6 +6,8 @@
 // License, v. 2.0. If a copy of the MPL was not distributed with this
 // file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+#include <CoreText/CoreText.h>
+
 #include <touch/touch.h>
 
 #import "View.h"
@@ -131,22 +133,47 @@ static void updateTilesPerSecond(UILabel *label)
     // as needed at the current zoom levels. I keep thinking about
     // "pixels" incorrectly.
 
-    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));
+    volatile static int number = 0;
+    int thisTile = number++;
+
+    if (!getenv("DRAW_ONLY_TILE") || thisTile == atoi(getenv("DRAW_ONLY_TILE")))
+        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 {
+        CGContextSetRGBFillColor(ctx, 1, 1, 1, 1);
+        CGContextFillRect(ctx, CGRectMake(0, 0, bb.size.width, bb.size.height));
+    }
 
     [self didRenderTile];
 
     CGContextRestoreGState(ctx);
 
-    // I am a bit confused about what tiles exactly I am drawing, so
-    // make it perfectly obvious by drawing borders around the tiles
-    CGContextSaveGState(ctx);
-    CGContextSetStrokeColorWithColor(ctx, [[UIColor colorWithRed:1 green:0 blue:0 alpha:0.5] CGColor]);
-    CGContextSetLineWidth(ctx, 1);
-    CGContextStrokeRect(ctx, bb);
-    CGContextRestoreGState(ctx);
+    if (getenv("DRAW_TILE_BORDERS")) {
+        // I am a bit confused about what tiles exactly I am drawing, so
+        // make it perfectly obvious by drawing borders around the tiles
+        CGContextSaveGState(ctx);
+        CGContextSetStrokeColorWithColor(ctx, [[UIColor colorWithRed:1 green:0 blue:0 alpha:0.5] CGColor]);
+        CGContextSetLineWidth(ctx, 1);
+        CGContextStrokeRect(ctx, bb);
+        CGContextRestoreGState(ctx);
+    }
+
+    if (getenv("DRAW_TILE_NUMBERS")) {
+        // Also draw the order number of the tile;)
+        CGContextSaveGState(ctx);
+        float scale = 1/[((View *) [self superview]) zoomScale];
+        NSString *s = [NSString stringWithFormat:@"%d", thisTile];
+        CFAttributedStringRef as = CFAttributedStringCreate(NULL, (__bridge CFStringRef)(s), NULL);
+        CTLineRef l = CTLineCreateWithAttributedString(as);
+        CGContextTranslateCTM(ctx, bb.origin.x, bb.origin.y);
+        CGContextScaleCTM(ctx, scale, scale);
+        CGContextSetTextPosition(ctx, 2, 12);
+        CGContextSetTextMatrix(ctx, CGAffineTransformScale(CGContextGetTextMatrix(ctx), 1, -1));
+        CTLineDraw(l, ctx);
+        CGContextRestoreGState(ctx);
+    }
 }
 
 @end