Add createTJunctionFreeRegion

T-junction free regions are useful for rendering regions with various
geometric transformations, and the Region's span-ordered, sorted rect
list supports T-junction free storage without modification.

This approach creates a T-junction free region by splitting each
rectangle that is part of a vertical T-junction. This approach is two
pass (up and down) so that divisions can trickle up/down to other
adjacent spans.

Change-Id: Ifcf5e6fe0034c96b00ef09a4433b2b0fce8f4300
This commit is contained in:
Chris Craik 2013-02-25 19:12:47 -08:00
parent 68a029edbb
commit 3e010f3138
6 changed files with 315 additions and 86 deletions

View File

@ -40,6 +40,8 @@ public:
explicit Region(const Rect& rhs); explicit Region(const Rect& rhs);
~Region(); ~Region();
static Region createTJunctionFreeRegion(const Region& r);
Region& operator = (const Region& rhs); Region& operator = (const Region& rhs);
inline bool isEmpty() const { return getBounds().isEmpty(); } inline bool isEmpty() const { return getBounds().isEmpty(); }

View File

@ -47,6 +47,11 @@ enum {
op_xor = region_operator<Rect>::op_xor op_xor = region_operator<Rect>::op_xor
}; };
enum {
direction_LTR,
direction_RTL
};
// ---------------------------------------------------------------------------- // ----------------------------------------------------------------------------
Region::Region() { Region::Region() {
@ -69,6 +74,133 @@ Region::~Region()
{ {
} }
/**
* Copy rects from the src vector into the dst vector, resolving vertical T-Junctions along the way
*
* First pass through, divideSpanRTL will be set because the 'previous span' (indexing into the dst
* vector) will be reversed. Each rectangle in the original list, starting from the bottom, will be
* compared with the span directly below, and subdivided as needed to resolve T-junctions.
*
* The resulting temporary vector will be a completely reversed copy of the original, without any
* bottom-up T-junctions.
*
* Second pass through, divideSpanRTL will be false since the previous span will index into the
* final, correctly ordered region buffer. Each rectangle will be compared with the span directly
* above it, and subdivided to resolve any remaining T-junctions.
*/
static void reverseRectsResolvingJunctions(const Rect* begin, const Rect* end,
Vector<Rect>& dst, int spanDirection) {
dst.clear();
const Rect* current = end - 1;
int lastTop = current->top;
// add first span immediately
do {
dst.add(*current);
current--;
} while (current->top == lastTop && current >= begin);
unsigned int beginLastSpan = -1;
unsigned int endLastSpan = -1;
int top = -1;
int bottom = -1;
// for all other spans, split if a t-junction exists in the span directly above
while (current >= begin) {
if (current->top != (current + 1)->top) {
// new span
if ((spanDirection == direction_RTL && current->bottom != (current + 1)->top) ||
(spanDirection == direction_LTR && current->top != (current + 1)->bottom)) {
// previous span not directly adjacent, don't check for T junctions
beginLastSpan = INT_MAX;
} else {
beginLastSpan = endLastSpan + 1;
}
endLastSpan = dst.size() - 1;
top = current->top;
bottom = current->bottom;
}
int left = current->left;
int right = current->right;
for (unsigned int prevIndex = beginLastSpan; prevIndex <= endLastSpan; prevIndex++) {
const Rect* prev = &dst[prevIndex];
if (spanDirection == direction_RTL) {
// iterating over previous span RTL, quit if it's too far left
if (prev->right <= left) break;
if (prev->right > left && prev->right < right) {
dst.add(Rect(prev->right, top, right, bottom));
right = prev->right;
}
if (prev->left > left && prev->left < right) {
dst.add(Rect(prev->left, top, right, bottom));
right = prev->left;
}
// if an entry in the previous span is too far right, nothing further left in the
// current span will need it
if (prev->left >= right) {
beginLastSpan = prevIndex;
}
} else {
// iterating over previous span LTR, quit if it's too far right
if (prev->left >= right) break;
if (prev->left > left && prev->left < right) {
dst.add(Rect(left, top, prev->left, bottom));
left = prev->left;
}
if (prev->right > left && prev->right < right) {
dst.add(Rect(left, top, prev->right, bottom));
left = prev->right;
}
// if an entry in the previous span is too far left, nothing further right in the
// current span will need it
if (prev->right <= left) {
beginLastSpan = prevIndex;
}
}
}
if (left < right) {
dst.add(Rect(left, top, right, bottom));
}
current--;
}
}
/**
* Creates a new region with the same data as the argument, but divides rectangles as necessary to
* remove T-Junctions
*
* Note: the output will not necessarily be a very efficient representation of the region, since it
* may be that a triangle-based approach would generate significantly simpler geometry
*/
Region Region::createTJunctionFreeRegion(const Region& r) {
if (r.isEmpty()) return r;
if (r.isRect()) return r;
Vector<Rect> reversed;
reverseRectsResolvingJunctions(r.begin(), r.end(), reversed, direction_RTL);
Region outputRegion;
reverseRectsResolvingJunctions(reversed.begin(), reversed.end(),
outputRegion.mStorage, direction_LTR);
outputRegion.mStorage.add(r.getBounds()); // to make region valid, mStorage must end with bounds
#if VALIDATE_REGIONS
validate(outputRegion, "T-Junction free region");
#endif
return outputRegion;
}
Region& Region::operator = (const Region& rhs) Region& Region::operator = (const Region& rhs)
{ {
#if VALIDATE_REGIONS #if VALIDATE_REGIONS

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@ -1,3 +1,27 @@
# Build the unit tests.
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
# Build the unit tests.
test_src_files := \
Region_test.cpp
shared_libraries := \
libui
static_libraries := \
libgtest \
libgtest_main
$(foreach file,$(test_src_files), \
$(eval include $(CLEAR_VARS)) \
$(eval LOCAL_SHARED_LIBRARIES := $(shared_libraries)) \
$(eval LOCAL_STATIC_LIBRARIES := $(static_libraries)) \
$(eval LOCAL_SRC_FILES := $(file)) \
$(eval LOCAL_MODULE := $(notdir $(file:%.cpp=%))) \
$(eval include $(BUILD_NATIVE_TEST)) \
)
# Build the unit tests. # Build the unit tests.
LOCAL_PATH:= $(call my-dir) LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS) include $(CLEAR_VARS)

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@ -0,0 +1,156 @@
/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define LOG_TAG "RegionTest"
#include <stdlib.h>
#include <ui/Region.h>
#include <ui/Rect.h>
#include <gtest/gtest.h>
namespace android {
class RegionTest : public testing::Test {
protected:
void checkVertTJunction(const Rect* lhs, const Rect* rhs) {
EXPECT_FALSE((rhs->right > lhs->left && rhs->right < lhs->right) ||
(rhs->left > lhs->left && rhs->left < lhs->right));
}
void verifyNoTJunctions(const Region& r) {
for (const Rect* current = r.begin(); current < r.end(); current++) {
for (const Rect* other = current - 1; other >= r.begin(); other--) {
if (other->bottom < current->top) break;
if (other->bottom != current->top) continue;
checkVertTJunction(current, other);
}
for (const Rect* other = current + 1; other < r.end(); other++) {
if (other->top > current->bottom) break;
if (other->top != current->bottom) continue;
checkVertTJunction(current, other);
}
}
}
void checkTJunctionFreeFromRegion(const Region& original, int expectedCount = -1) {
Region modified = Region::createTJunctionFreeRegion(original);
verifyNoTJunctions(modified);
if (expectedCount != -1) {
EXPECT_EQ(modified.end() - modified.begin(), expectedCount);
}
EXPECT_TRUE((original ^ modified).isEmpty());
}
};
TEST_F(RegionTest, MinimalDivision_TJunction) {
Region r;
// | x |
// |xxx|
r.clear();
r.orSelf(Rect(1, 0, 2, 1));
r.orSelf(Rect(0, 1, 3, 2));
checkTJunctionFreeFromRegion(r, 4);
// | x |
// | |
// |xxx|
r.clear();
r.orSelf(Rect(1, 0, 2, 1));
r.orSelf(Rect(0, 2, 3, 3));
checkTJunctionFreeFromRegion(r, 2);
}
TEST_F(RegionTest, Trivial_TJunction) {
Region r;
checkTJunctionFreeFromRegion(r);
r.orSelf(Rect(100, 100, 500, 500));
checkTJunctionFreeFromRegion(r);
}
TEST_F(RegionTest, Simple_TJunction) {
Region r;
// | x |
// |xxxx|
// |xxxx|
// |xxxx|
r.clear();
r.orSelf(Rect(1, 0, 2, 1));
r.orSelf(Rect(0, 1, 3, 3));
checkTJunctionFreeFromRegion(r);
// | x |
// |xx |
// |xxx|
r.clear();
r.orSelf(Rect(2,0,4,2));
r.orSelf(Rect(0,2,4,4));
r.orSelf(Rect(0,4,6,6));
checkTJunctionFreeFromRegion(r);
// |x x|
// |xxx|
// |x x|
r.clear();
r.orSelf(Rect(0,0,2,6));
r.orSelf(Rect(4,0,6,6));
r.orSelf(Rect(0,2,6,4));
checkTJunctionFreeFromRegion(r);
// |xxx|
// | x |
// | x |
r.clear();
r.orSelf(Rect(0,0,6,2));
r.orSelf(Rect(2,2,4,6));
checkTJunctionFreeFromRegion(r);
}
TEST_F(RegionTest, Bigger_TJunction) {
Region r;
// |xxxx |
// | xxxx |
// | xxxx |
// | xxxx|
for (int i = 0; i < 4; i++) {
r.orSelf(Rect(i,i,i+4,i+1));
}
checkTJunctionFreeFromRegion(r, 16);
}
#define ITER_MAX 1000
#define X_MAX 8
#define Y_MAX 8
TEST_F(RegionTest, Random_TJunction) {
Region r;
srandom(12345);
for (int iter = 0; iter < ITER_MAX; iter++) {
r.clear();
for (int i = 0; i < X_MAX; i++) {
for (int j = 0; j < Y_MAX; j++) {
if (random() % 2) {
r.orSelf(Rect(i, j, i + 1, j + 1));
}
}
}
checkTJunctionFreeFromRegion(r);
}
}
}; // namespace android

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@ -1,16 +0,0 @@
LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)
LOCAL_SRC_FILES:= \
region.cpp
LOCAL_SHARED_LIBRARIES := \
libcutils \
libutils \
libui
LOCAL_MODULE:= test-region
LOCAL_MODULE_TAGS := tests
include $(BUILD_EXECUTABLE)

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@ -1,69 +0,0 @@
/*
* Copyright (C) 2009 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define LOG_TAG "Region"
#include <stdio.h>
#include <utils/Debug.h>
#include <ui/Rect.h>
#include <ui/Region.h>
using namespace android;
int main()
{
Region empty;
Region reg0( Rect( 0, 0, 100, 100 ) );
Region reg1 = reg0;
Region reg2, reg3;
Region reg4 = empty | reg1;
Region reg5 = reg1 | empty;
reg4.dump("reg4");
reg5.dump("reg5");
reg0.dump("reg0");
reg1.dump("reg1");
reg0 = reg0 | reg0.translate(150, 0);
reg0.dump("reg0");
reg1.dump("reg1");
reg0 = reg0 | reg0.translate(300, 0);
reg0.dump("reg0");
reg1.dump("reg1");
//reg2 = reg0 | reg0.translate(0, 100);
//reg0.dump("reg0");
//reg1.dump("reg1");
//reg2.dump("reg2");
//reg3 = reg0 | reg0.translate(0, 150);
//reg0.dump("reg0");
//reg1.dump("reg1");
//reg2.dump("reg2");
//reg3.dump("reg3");
ALOGD("---");
reg2 = reg0 | reg0.translate(100, 0);
reg0.dump("reg0");
reg1.dump("reg1");
reg2.dump("reg2");
return 0;
}