Simplify mask/clip intersection, making sure to explicitly check for an empty mask.

Previously we were only asserting the mask wasn't empty, which isn't necessarily true when we're given pathological float coordinates like +Inf or NaN.

A local run of nanobench --match text_ was not able to show this is faster or slower.

This patch fixed this first Chrome bug on my desktop, and the second is probably a dupe.
BUG=chromium:619378,chromium:613912

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2073873002

Review-Url: https://codereview.chromium.org/2073873002

2 files changed, 28 insertions, 4 deletions

diff --git a/src/core/SkDraw.cpp b/src/core/SkDraw.cpp
index 24fc9064a6..9a0509c488 100644
--- a/src/core/SkDraw.cpp
+++ b/src/core/SkDraw.cpp
@@ -1457,10 +1457,13 @@ public:
     void operator()(const SkGlyph& glyph, SkPoint position, SkPoint rounding) {
         position += rounding;
         // Prevent glyphs from being drawn outside of or straddling the edge of device space.
-        if (position.fX > INT_MAX - (INT16_MAX + UINT16_MAX) ||
-            position.fX < INT_MIN - (INT16_MIN + 0 /*UINT16_MIN*/) ||
-            position.fY > INT_MAX - (INT16_MAX + UINT16_MAX) ||
-            position.fY < INT_MIN - (INT16_MIN + 0 /*UINT16_MIN*/)) {
+        // Comparisons written a little weirdly so that NaN coordinates are treated safely.
+        auto gt = [](float a, int b) { return !(a <= (float)b); };
+        auto lt = [](float a, int b) { return !(a >= (float)b); };
+        if (gt(position.fX, INT_MAX - (INT16_MAX + UINT16_MAX)) ||
+            lt(position.fX, INT_MIN - (INT16_MIN + 0 /*UINT16_MIN*/)) ||
+            gt(position.fY, INT_MAX - (INT16_MAX + UINT16_MAX)) ||
+            lt(position.fY, INT_MIN - (INT16_MIN + 0 /*UINT16_MIN*/))) {
             return;
         }
 
@@ -1476,6 +1479,7 @@ public:
 
         SkMask mask;
         mask.fBounds.set(left, top, right, bottom);
+        SkASSERT(!mask.fBounds.isEmpty());
 
         if (fUseRegionToDraw) {
             SkRegion::Cliperator clipper(*fClip, mask.fBounds);
diff --git a/tests/DrawTextTest.cpp b/tests/DrawTextTest.cpp
index f2da450fe8..bf9bd39f8d 100644
--- a/tests/DrawTextTest.cpp
+++ b/tests/DrawTextTest.cpp
@@ -11,8 +11,10 @@
 #include "SkPaint.h"
 #include "SkPoint.h"
 #include "SkRect.h"
+#include "SkSurface.h"
 #include "SkTypes.h"
 #include "Test.h"
+#include <math.h>
 
 static const SkColor bgColor = SK_ColorWHITE;
 
@@ -111,3 +113,21 @@ DEF_TEST(DrawText, reporter) {
         }
     }
 }
+
+// Test drawing text at some unusual coordinates.
+// We measure success by not crashing or asserting.
+DEF_TEST(DrawText_weirdCoordinates, r) {
+    auto surface = SkSurface::MakeRasterN32Premul(10,10);
+    auto canvas = surface->getCanvas();
+
+    SkScalar oddballs[] = { 0.0f, (float)INFINITY, (float)NAN, 34359738368.0f };
+
+    for (auto x : oddballs) {
+        canvas->drawText("a", 1, +x, 0.0f, SkPaint());
+        canvas->drawText("a", 1, -x, 0.0f, SkPaint());
+    }
+    for (auto y : oddballs) {
+        canvas->drawText("a", 1, 0.0f, +y, SkPaint());
+        canvas->drawText("a", 1, 0.0f, -y, SkPaint());
+    }
+}