Adding my Bitmap2Path sample for 1on1 meeting.

BUG=
R=reed@google.com, borenet@google.com

Author: dierk@google.com

Review URL: https://chromiumcodereview.appspot.com/16829003

git-svn-id: http://skia.googlecode.com/svn/trunk@9843 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 150 insertions, 0 deletions

diff --git a/src/utils/SkPathUtils.cpp b/src/utils/SkPathUtils.cpp
new file mode 100644
index 0000000000..3d9bc08a1f
--- /dev/null
+++ b/src/utils/SkPathUtils.cpp
@@ -0,0 +1,150 @@
+/*
+ *  CAUTION: EXPERIMENTAL CODE
+ *
+ *  This code is not to be used and will not be supported
+ *  if it fails on you. DO NOT USE!
+ *
+ */
+
+#include "SkPathUtils.h"
+
+#include "SkPath.h"
+#include "SkPathOps.h" // this can't be found, how do I link it?
+#include "SkRegion.h"
+
+typedef void (*line2path)(SkPath*, const char*, int, int);
+#define SQRT_2 1.41421356237f
+#define ON  0xFF000000 // black pixel
+#define OFF 0x00000000 // transparent pixel
+
+// assumes stride is in bytes
+/*
+static void FillRandomBits( int chars, char* bits ){
+    SkTime time;
+    SkMWCRandom rand = SkMWCRandom( time.GetMSecs() );
+
+    for (int i = 0; i < chars; ++i){
+        bits[i] = rand.nextU();
+    }
+}OA
+*/    
+
+static int GetBit( const char* buffer, int x ) {
+    int byte = x >> 3;
+    int bit = x & 7;
+
+    return buffer[byte] & (128 >> bit);
+}
+
+/*
+static void Line2path_pixel(SkPath* path, const char* line,
+                            int lineIdx, int width) {
+    for (int i = 0; i < width; ++i) {
+        // simply makes every ON pixel into a rect path
+        if (GetBit(line,i)) {
+            path->addRect(SkRect::MakeXYWH(i, lineIdx, 1, 1),
+                          SkPath::kCW_Direction);
+        }
+    }
+}
+
+static void Line2path_pixelCircle(SkPath* path, const char* line,
+                                  int lineIdx, int width) {
+    for (int i = 0; i < width; ++i) {
+        // simply makes every ON pixel into a circle path
+        if (GetBit(line,i)) {
+            path->addCircle(i + SK_ScalarHalf,
+                            lineIdx + SK_ScalarHalf,
+                            SkFloatToScalar(SQRT_2 / 2.0f));
+        }
+    }
+}
+*/
+
+static void Line2path_span(SkPath* path, const char* line,
+                           int lineIdx, int width) {
+    bool inRun = 0;
+    int start = 1;
+
+    for (int i = 0; i < width; ++i) {
+        int curPixel = GetBit(line,i);
+
+        if ( (curPixel!=0) != inRun ) { // if transition
+            if (curPixel) { // if transition on
+                inRun = 1;
+                start = i; // mark beginning of span
+            }else { // if transition off add the span as a path
+                inRun = 0;
+                path->addRect(SkRect::MakeXYWH(start, lineIdx, i-start, 1),
+                              SkPath::kCW_Direction);
+            }
+        }
+    }
+
+    if (inRun==1) { // close any open spans
+        int end = 0;
+        if ( GetBit(line,width-1) ) ++end;
+        path->addRect(SkRect::MakeXYWH(start, lineIdx,
+                                       width - 1 + end - start, 1),
+                      SkPath::kCW_Direction);
+    } else if ( GetBit(line,width-1) ) { // if last pixel on add rect
+        path->addRect(SkRect::MakeXYWH(width-1, lineIdx, 1, 1),
+                      SkPath::kCW_Direction);
+    }
+}
+
+void SkPathUtils::BitsToPath_Path(SkPath* path,
+                        const char* bitmap,
+                        int h, int w, int stride) {
+    // loop for every line in bitmap
+    for (int i = 0; i < h; ++i) {
+        // fn ptr handles each line separately
+        //l2p_fn(path, &bitmap[i*stride], i, w);
+        Line2path_span(path, &bitmap[i*stride], i, w);
+    }
+    Simplify(*path, path); // simplify resulting bitmap
+}
+
+void SkPathUtils::BitsToPath_Region(SkPath* path,
+                               const char* bitmap,
+                               int h, int w, int stride) {
+    SkRegion region;
+
+    // loop for each line
+    for (int y = 0; y < h; ++y){
+        bool inRun = 0;
+        int start = 1;
+        const char* line = &bitmap[y * stride];
+        
+        // loop for each pixel 
+        for (int i = 0; i < w; ++i) {
+            int curPixel = GetBit(line,i);
+            
+            if ( (curPixel!=0) != inRun ) { // if transition
+                if (curPixel) { // if transition on
+                    inRun = 1;
+                    start = i; // mark beginning of span
+                }else { // if transition off add the span as a path
+                    inRun = 0;
+                    //add here
+                    region.op(SkIRect::MakeXYWH(start, y, i-start, 1),
+                              SkRegion::kUnion_Op );
+                }
+            }
+        }
+        if (inRun==1) { // close any open spans
+            int end = 0;
+            if ( GetBit(line,w-1) ) ++end;
+            // add the thing here
+            region.op(SkIRect::MakeXYWH(start, y, w-1-start+end, 1),
+                      SkRegion::kUnion_Op );
+            
+        } else if ( GetBit(line,w-1) ) { // if last pixel on add rect
+            // add the thing here
+            region.op(SkIRect::MakeXYWH(w-1, y, 1, 1),
+                      SkRegion::kUnion_Op );
+        }
+    }
+    // convert region to path
+    region.getBoundaryPath(path);
+}