From 1f797292884f0007a9c408184812afab36952412 Mon Sep 17 00:00:00 2001
From: Pascal Terjan <pterjan@linuxfr.org>
Date: Sun, 19 Jul 2009 20:37:12 +0000
Subject: [PATCH]  * When blitting, only add dirty rectangles on changed   
 lines, or on changed chars if we have a mask

---
 caca/string.c   | 22 +++++++++++++++-------
 tests/dirty.cpp | 24 ++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 7 deletions(-)

diff --git a/caca/string.c b/caca/string.c
index bff1436..62b709f 100644
--- a/caca/string.c
+++ b/caca/string.c
@@ -448,14 +448,25 @@ int caca_blit(caca_canvas_t *dst, int x, int y,
                 if(mask->chars[srcix + i] == (uint32_t)' ')
                     continue;
 
-                dst->chars[dstix + i] = src->chars[srcix + i];
-                dst->attrs[dstix + i] = src->attrs[srcix + i];
+                if(dst->chars[dstix + i] != src->chars[srcix + i] ||
+                   dst->attrs[dstix + i] != src->attrs[srcix + i])
+                {
+                    dst->chars[dstix + i] = src->chars[srcix + i];
+                    dst->attrs[dstix + i] = src->attrs[srcix + i];
+                    caca_add_dirty_rect(dst, x + starti + i, y + j, 1, 1);
+                }
             }
         }
         else
         {
-            memcpy(dst->chars + dstix, src->chars + srcix, stride * 4);
-            memcpy(dst->attrs + dstix, src->attrs + srcix, stride * 4);
+            if(memcmp(dst->chars + dstix, src->chars + srcix, stride * 4) ||
+               memcmp(dst->attrs + dstix, src->attrs + srcix, stride * 4))
+            {
+                /* FIXME be more precise ? */
+                memcpy(dst->chars + dstix, src->chars + srcix, stride * 4);
+                memcpy(dst->attrs + dstix, src->attrs + srcix, stride * 4);
+                caca_add_dirty_rect(dst, x + starti, y + j, stride, 1);
+            }
         }
 
         /* Fix split fullwidth chars */
@@ -466,9 +477,6 @@ int caca_blit(caca_canvas_t *dst, int x, int y,
             dst->chars[dstix + stride - 1] = ' ';
     }
 
-    caca_add_dirty_rect(dst, starti + x - bleed_left, startj + y,
-                        endi - starti + bleed_left + bleed_right,
-                        endj - startj);
 
     return 0;
 }
diff --git a/tests/dirty.cpp b/tests/dirty.cpp
index f64d878..6d285c0 100644
--- a/tests/dirty.cpp
+++ b/tests/dirty.cpp
@@ -28,6 +28,7 @@ class DirtyTest : public CppUnit::TestCase
     CPPUNIT_TEST(test_put_char_dirty);
     CPPUNIT_TEST(test_put_char_not_dirty);
     CPPUNIT_TEST(test_box);
+    CPPUNIT_TEST(test_blit);
     CPPUNIT_TEST_SUITE_END();
 
 public:
@@ -185,6 +186,29 @@ public:
         CPPUNIT_ASSERT_EQUAL(i, 0);
     }
 
+    void test_blit()
+    {
+        caca_canvas_t *cv, *cv2;
+        int i, dx, dy, dw, dh;
+
+        cv = caca_create_canvas(WIDTH, HEIGHT);
+        caca_clear_dirty_rect_list(cv);
+        cv2 = caca_create_canvas(2, 2);
+        caca_fill_box(cv2, 0, 0, 2, 1, 'x');
+
+        caca_blit(cv, 1, 1, cv2, NULL);
+        i = caca_get_dirty_rect_count(cv);
+        CPPUNIT_ASSERT_EQUAL(i, 1);
+        caca_get_dirty_rect(cv, 0, &dx, &dy, &dw, &dh);
+
+        /* Check that blitting a canvas make a dirty rectangle
+         * only for modified lines */
+        CPPUNIT_ASSERT(dx == 1);
+        CPPUNIT_ASSERT(dy == 1);
+        CPPUNIT_ASSERT(dw >= 2);
+        CPPUNIT_ASSERT(dh == 1);
+    }
+
 private:
     static int const WIDTH = 80, HEIGHT = 50;
 };