OpenGLRenderer.cpp revision f18fd99b5c182329cd8936a9611f0103d8ece44a
1/* 2 * Copyright (C) 2010 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17#define LOG_TAG "OpenGLRenderer" 18 19#include <stdlib.h> 20#include <stdint.h> 21#include <sys/types.h> 22 23#include <SkCanvas.h> 24 25#include <cutils/properties.h> 26#include <utils/Log.h> 27 28#include "OpenGLRenderer.h" 29 30namespace android { 31namespace uirenderer { 32 33/////////////////////////////////////////////////////////////////////////////// 34// Defines 35/////////////////////////////////////////////////////////////////////////////// 36 37// These properties are defined in mega-bytes 38#define PROPERTY_TEXTURE_CACHE_SIZE "ro.hwui.texture_cache_size" 39#define PROPERTY_LAYER_CACHE_SIZE "ro.hwui.layer_cache_size" 40 41#define DEFAULT_TEXTURE_CACHE_SIZE 20 42#define DEFAULT_LAYER_CACHE_SIZE 10 43 44// Converts a number of mega-bytes into bytes 45#define MB(s) s * 1024 * 1024 46 47// Generates simple and textured vertices 48#define SV(x, y) { { x, y } } 49#define FV(x, y, u, v) { { x, y }, { u, v } } 50 51/////////////////////////////////////////////////////////////////////////////// 52// Globals 53/////////////////////////////////////////////////////////////////////////////// 54 55static const SimpleVertex gDrawColorVertices[] = { 56 SV(0.0f, 0.0f), 57 SV(1.0f, 0.0f), 58 SV(0.0f, 1.0f), 59 SV(1.0f, 1.0f) 60}; 61static const GLsizei gDrawColorVertexStride = sizeof(SimpleVertex); 62static const GLsizei gDrawColorVertexCount = 4; 63 64// This array is never used directly but used as a memcpy source in the 65// OpenGLRenderer constructor 66static const TextureVertex gDrawTextureVertices[] = { 67 FV(0.0f, 0.0f, 0.0f, 0.0f), 68 FV(1.0f, 0.0f, 1.0f, 0.0f), 69 FV(0.0f, 1.0f, 0.0f, 1.0f), 70 FV(1.0f, 1.0f, 1.0f, 1.0f) 71}; 72static const GLsizei gDrawTextureVertexStride = sizeof(TextureVertex); 73static const GLsizei gDrawTextureVertexCount = 4; 74 75// In this array, the index of each Blender equals the value of the first 76// entry. For instance, gBlends[1] == gBlends[SkXfermode::kSrc_Mode] 77static const Blender gBlends[] = { 78 { SkXfermode::kClear_Mode, GL_ZERO, GL_ZERO }, 79 { SkXfermode::kSrc_Mode, GL_ONE, GL_ZERO }, 80 { SkXfermode::kDst_Mode, GL_ZERO, GL_ONE }, 81 { SkXfermode::kSrcOver_Mode, GL_ONE, GL_ONE_MINUS_SRC_ALPHA }, 82 { SkXfermode::kDstOver_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ONE }, 83 { SkXfermode::kSrcIn_Mode, GL_DST_ALPHA, GL_ZERO }, 84 { SkXfermode::kDstIn_Mode, GL_ZERO, GL_SRC_ALPHA }, 85 { SkXfermode::kSrcOut_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ZERO }, 86 { SkXfermode::kDstOut_Mode, GL_ZERO, GL_ONE_MINUS_SRC_ALPHA }, 87 { SkXfermode::kSrcATop_Mode, GL_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA }, 88 { SkXfermode::kDstATop_Mode, GL_ONE_MINUS_DST_ALPHA, GL_SRC_ALPHA }, 89 { SkXfermode::kXor_Mode, GL_ONE_MINUS_DST_ALPHA, GL_ONE_MINUS_SRC_ALPHA } 90}; 91 92/////////////////////////////////////////////////////////////////////////////// 93// Constructors/destructor 94/////////////////////////////////////////////////////////////////////////////// 95 96OpenGLRenderer::OpenGLRenderer(): 97 mTextureCache(MB(DEFAULT_TEXTURE_CACHE_SIZE)), 98 mLayerCache(MB(DEFAULT_LAYER_CACHE_SIZE)) { 99 LOGD("Create OpenGLRenderer"); 100 101 char property[PROPERTY_VALUE_MAX]; 102 if (property_get(PROPERTY_TEXTURE_CACHE_SIZE, property, NULL) > 0) { 103 LOGD(" Setting texture cache size to %sMB", property); 104 mTextureCache.setMaxSize(MB(atoi(property))); 105 } else { 106 LOGD(" Using default texture cache size of %dMB", DEFAULT_TEXTURE_CACHE_SIZE); 107 } 108 109 if (property_get(PROPERTY_LAYER_CACHE_SIZE, property, NULL) > 0) { 110 LOGD(" Setting layer cache size to %sMB", property); 111 mLayerCache.setMaxSize(MB(atoi(property))); 112 } else { 113 LOGD(" Using default layer cache size of %dMB", DEFAULT_LAYER_CACHE_SIZE); 114 } 115 116 mDrawColorShader = new DrawColorProgram; 117 mDrawTextureShader = new DrawTextureProgram; 118 119 memcpy(mDrawTextureVertices, gDrawTextureVertices, sizeof(gDrawTextureVertices)); 120} 121 122OpenGLRenderer::~OpenGLRenderer() { 123 LOGD("Destroy OpenGLRenderer"); 124 125 mTextureCache.clear(); 126 mLayerCache.clear(); 127} 128 129/////////////////////////////////////////////////////////////////////////////// 130// Setup 131/////////////////////////////////////////////////////////////////////////////// 132 133void OpenGLRenderer::setViewport(int width, int height) { 134 glViewport(0, 0, width, height); 135 136 mat4 ortho; 137 ortho.loadOrtho(0, width, height, 0, -1, 1); 138 ortho.copyTo(mOrthoMatrix); 139 140 mWidth = width; 141 mHeight = height; 142 mFirstSnapshot.height = height; 143} 144 145void OpenGLRenderer::prepare() { 146 mSnapshot = &mFirstSnapshot; 147 mSaveCount = 0; 148 149 glDisable(GL_SCISSOR_TEST); 150 151 glClearColor(0.0f, 0.0f, 0.0f, 0.0f); 152 glClear(GL_COLOR_BUFFER_BIT); 153 154 glEnable(GL_SCISSOR_TEST); 155 glScissor(0, 0, mWidth, mHeight); 156 157 mSnapshot->clipRect.set(0.0f, 0.0f, mWidth, mHeight); 158} 159 160/////////////////////////////////////////////////////////////////////////////// 161// State management 162/////////////////////////////////////////////////////////////////////////////// 163 164int OpenGLRenderer::getSaveCount() const { 165 return mSaveCount; 166} 167 168int OpenGLRenderer::save(int flags) { 169 return saveSnapshot(); 170} 171 172void OpenGLRenderer::restore() { 173 if (mSaveCount == 0) return; 174 175 if (restoreSnapshot()) { 176 setScissorFromClip(); 177 } 178} 179 180void OpenGLRenderer::restoreToCount(int saveCount) { 181 if (saveCount <= 0 || saveCount > mSaveCount) return; 182 183 bool restoreClip = false; 184 185 while (mSaveCount != saveCount - 1) { 186 restoreClip |= restoreSnapshot(); 187 } 188 189 if (restoreClip) { 190 setScissorFromClip(); 191 } 192} 193 194int OpenGLRenderer::saveSnapshot() { 195 mSnapshot = new Snapshot(mSnapshot); 196 return ++mSaveCount; 197} 198 199bool OpenGLRenderer::restoreSnapshot() { 200 bool restoreClip = mSnapshot->flags & Snapshot::kFlagClipSet; 201 bool restoreLayer = mSnapshot->flags & Snapshot::kFlagIsLayer; 202 bool restoreOrtho = mSnapshot->flags & Snapshot::kFlagDirtyOrtho; 203 204 sp<Snapshot> current = mSnapshot; 205 sp<Snapshot> previous = mSnapshot->previous; 206 207 if (restoreOrtho) { 208 memcpy(mOrthoMatrix, current->orthoMatrix, sizeof(mOrthoMatrix)); 209 } 210 211 if (restoreLayer) { 212 composeLayer(current, previous); 213 } 214 215 mSnapshot = previous; 216 mSaveCount--; 217 218 return restoreClip; 219} 220 221void OpenGLRenderer::composeLayer(sp<Snapshot> current, sp<Snapshot> previous) { 222 if (!current->layer) { 223 LOGE("Attempting to compose a layer that does not exist"); 224 return; 225 } 226 227 // Unbind current FBO and restore previous one 228 // Most of the time, previous->fbo will be 0 to bind the default buffer 229 glBindFramebuffer(GL_FRAMEBUFFER, previous->fbo); 230 231 // Restore the clip from the previous snapshot 232 const Rect& clip = previous->getMappedClip(); 233 glScissor(clip.left, mHeight - clip.bottom, clip.getWidth(), clip.getHeight()); 234 235 Layer* layer = current->layer; 236 237 // Compute the correct texture coordinates for the FBO texture 238 // The texture is currently as big as the window but drawn with 239 // a quad of the appropriate size 240 const Rect& rect = layer->layer; 241 242 drawTextureRect(rect.left, rect.top, rect.right, rect.bottom, 243 layer->texture, layer->alpha, layer->mode, layer->blend, true); 244 245 LayerSize size(rect.getWidth(), rect.getHeight()); 246 // Failing to add the layer to the cache should happen only if the 247 // layer is too large 248 if (!mLayerCache.put(size, layer)) { 249 LAYER_LOGD("Deleting layer"); 250 251 glDeleteFramebuffers(1, &layer->fbo); 252 glDeleteTextures(1, &layer->texture); 253 254 delete layer; 255 } 256} 257 258/////////////////////////////////////////////////////////////////////////////// 259// Layers 260/////////////////////////////////////////////////////////////////////////////// 261 262int OpenGLRenderer::saveLayer(float left, float top, float right, float bottom, 263 const SkPaint* p, int flags) { 264 int count = saveSnapshot(); 265 266 int alpha = 255; 267 SkXfermode::Mode mode; 268 269 if (p) { 270 alpha = p->getAlpha(); 271 const bool isMode = SkXfermode::IsMode(p->getXfermode(), &mode); 272 if (!isMode) { 273 // Assume SRC_OVER 274 mode = SkXfermode::kSrcOver_Mode; 275 } 276 } else { 277 mode = SkXfermode::kSrcOver_Mode; 278 } 279 280 createLayer(mSnapshot, left, top, right, bottom, alpha, mode, flags); 281 282 return count; 283} 284 285int OpenGLRenderer::saveLayerAlpha(float left, float top, float right, float bottom, 286 int alpha, int flags) { 287 int count = saveSnapshot(); 288 createLayer(mSnapshot, left, top, right, bottom, alpha, SkXfermode::kSrcOver_Mode, flags); 289 return count; 290} 291 292bool OpenGLRenderer::createLayer(sp<Snapshot> snapshot, float left, float top, 293 float right, float bottom, int alpha, SkXfermode::Mode mode,int flags) { 294 295 LAYER_LOGD("Requesting layer %dx%d", size.width, size.height); 296 LAYER_LOGD("Layer cache size = %d", mLayerCache.getSize()); 297 298 GLuint previousFbo = snapshot->previous.get() ? snapshot->previous->fbo : 0; 299 LayerSize size(right - left, bottom - top); 300 301 // TODO VERY IMPORTANT: Fix TextView to not call saveLayer() all the time 302 Layer* layer = mLayerCache.get(size, previousFbo); 303 if (!layer) { 304 return false; 305 } 306 307 glBindFramebuffer(GL_FRAMEBUFFER, layer->fbo); 308 309 // Clear the FBO 310 glDisable(GL_SCISSOR_TEST); 311 glClearColor(0.0f, 0.0f, 0.0f, 0.0f); 312 glClear(GL_COLOR_BUFFER_BIT); 313 glEnable(GL_SCISSOR_TEST); 314 315 // Save the layer in the snapshot 316 snapshot->flags |= Snapshot::kFlagIsLayer; 317 layer->mode = mode; 318 layer->alpha = alpha / 255.0f; 319 layer->layer.set(left, top, right, bottom); 320 321 snapshot->layer = layer; 322 snapshot->fbo = layer->fbo; 323 324 // Creates a new snapshot to draw into the FBO 325 saveSnapshot(); 326 // TODO: This doesn't preserve other transformations (check Skia first) 327 mSnapshot->transform.loadTranslate(-left, -top, 0.0f); 328 mSnapshot->clipRect.set(left, top, right, bottom); 329 mSnapshot->height = bottom - top; 330 setScissorFromClip(); 331 332 mSnapshot->flags = Snapshot::kFlagDirtyTransform | Snapshot::kFlagDirtyOrtho | 333 Snapshot::kFlagClipSet; 334 memcpy(mSnapshot->orthoMatrix, mOrthoMatrix, sizeof(mOrthoMatrix)); 335 336 // Change the ortho projection 337 mat4 ortho; 338 ortho.loadOrtho(0.0f, right - left, bottom - top, 0.0f, 0.0f, 1.0f); 339 ortho.copyTo(mOrthoMatrix); 340 341 return true; 342} 343 344/////////////////////////////////////////////////////////////////////////////// 345// Transforms 346/////////////////////////////////////////////////////////////////////////////// 347 348void OpenGLRenderer::translate(float dx, float dy) { 349 mSnapshot->transform.translate(dx, dy, 0.0f); 350 mSnapshot->flags |= Snapshot::kFlagDirtyTransform; 351} 352 353void OpenGLRenderer::rotate(float degrees) { 354 mSnapshot->transform.rotate(degrees, 0.0f, 0.0f, 1.0f); 355 mSnapshot->flags |= Snapshot::kFlagDirtyTransform; 356} 357 358void OpenGLRenderer::scale(float sx, float sy) { 359 mSnapshot->transform.scale(sx, sy, 1.0f); 360 mSnapshot->flags |= Snapshot::kFlagDirtyTransform; 361} 362 363void OpenGLRenderer::setMatrix(SkMatrix* matrix) { 364 mSnapshot->transform.load(*matrix); 365 mSnapshot->flags |= Snapshot::kFlagDirtyTransform; 366} 367 368void OpenGLRenderer::getMatrix(SkMatrix* matrix) { 369 mSnapshot->transform.copyTo(*matrix); 370} 371 372void OpenGLRenderer::concatMatrix(SkMatrix* matrix) { 373 mat4 m(*matrix); 374 mSnapshot->transform.multiply(m); 375 mSnapshot->flags |= Snapshot::kFlagDirtyTransform; 376} 377 378/////////////////////////////////////////////////////////////////////////////// 379// Clipping 380/////////////////////////////////////////////////////////////////////////////// 381 382void OpenGLRenderer::setScissorFromClip() { 383 const Rect& clip = mSnapshot->getMappedClip(); 384 glScissor(clip.left, mSnapshot->height - clip.bottom, clip.getWidth(), clip.getHeight()); 385} 386 387const Rect& OpenGLRenderer::getClipBounds() { 388 return mSnapshot->clipRect; 389} 390 391bool OpenGLRenderer::quickReject(float left, float top, float right, float bottom) { 392 /* 393 * The documentation of quickReject() indicates that the specified rect 394 * is transformed before being compared to the clip rect. However, the 395 * clip rect is not stored transformed in the snapshot and can thus be 396 * compared directly 397 * 398 * The following code can be used instead to performed a mapped comparison: 399 * 400 * mSnapshot->transform.mapRect(r); 401 * const Rect& clip = mSnapshot->getMappedClip(); 402 * return !clip.intersects(r); 403 */ 404 Rect r(left, top, right, bottom); 405 return !mSnapshot->clipRect.intersects(r); 406} 407 408bool OpenGLRenderer::clipRect(float left, float top, float right, float bottom) { 409 bool clipped = mSnapshot->clipRect.intersect(left, top, right, bottom); 410 if (clipped) { 411 mSnapshot->flags |= Snapshot::kFlagClipSet; 412 setScissorFromClip(); 413 } 414 return clipped; 415} 416 417/////////////////////////////////////////////////////////////////////////////// 418// Drawing 419/////////////////////////////////////////////////////////////////////////////// 420 421void OpenGLRenderer::drawBitmap(SkBitmap* bitmap, float left, float top, const SkPaint* paint) { 422 const Texture* texture = mTextureCache.get(bitmap); 423 424 int alpha; 425 SkXfermode::Mode mode; 426 getAlphaAndMode(paint, &alpha, &mode); 427 428 drawTextureRect(left, top, left + texture->width, top + texture->height, texture->id, 429 alpha / 255.0f, mode, texture->blend, true); 430} 431 432void OpenGLRenderer::drawBitmap(SkBitmap* bitmap, const SkMatrix* matrix, const SkPaint* paint) { 433 Rect r(0.0f, 0.0f, bitmap->width(), bitmap->height()); 434 const mat4 transform(*matrix); 435 transform.mapRect(r); 436 437 const Texture* texture = mTextureCache.get(bitmap); 438 439 int alpha; 440 SkXfermode::Mode mode; 441 getAlphaAndMode(paint, &alpha, &mode); 442 443 drawTextureRect(r.left, r.top, r.right, r.bottom, texture->id, 444 alpha / 255.0f, mode, texture->blend, true); 445} 446 447void OpenGLRenderer::drawBitmap(SkBitmap* bitmap, 448 float srcLeft, float srcTop, float srcRight, float srcBottom, 449 float dstLeft, float dstTop, float dstRight, float dstBottom, 450 const SkPaint* paint) { 451 const Texture* texture = mTextureCache.get(bitmap); 452 453 int alpha; 454 SkXfermode::Mode mode; 455 getAlphaAndMode(paint, &alpha, &mode); 456 457 const float width = texture->width; 458 const float height = texture->height; 459 460 const float u1 = srcLeft / width; 461 const float v1 = srcTop / height; 462 const float u2 = srcRight / width; 463 const float v2 = srcBottom / height; 464 465 resetDrawTextureTexCoords(u1, v1, u2, v2); 466 467 drawTextureRect(dstLeft, dstTop, dstRight, dstBottom, texture->id, 468 alpha / 255.0f, mode, texture->blend, true); 469 470 resetDrawTextureTexCoords(0.0f, 0.0f, 1.0f, 1.0f); 471} 472 473void OpenGLRenderer::drawPatch(SkBitmap* bitmap, Res_png_9patch* patch, 474 float left, float top, float right, float bottom, const SkPaint* paint) { 475 // TODO: Implement 476 LOGD("Draw 9patch, paddingLeft=%d", patch->paddingLeft); 477} 478 479void OpenGLRenderer::drawColor(int color, SkXfermode::Mode mode) { 480 const Rect& clip = mSnapshot->clipRect; 481 drawColorRect(clip.left, clip.top, clip.right, clip.bottom, color, mode); 482} 483 484void OpenGLRenderer::drawRect(float left, float top, float right, float bottom, const SkPaint* p) { 485 SkXfermode::Mode mode; 486 487 const bool isMode = SkXfermode::IsMode(p->getXfermode(), &mode); 488 if (!isMode) { 489 // Assume SRC_OVER 490 mode = SkXfermode::kSrcOver_Mode; 491 } 492 493 // Skia draws using the color's alpha channel if < 255 494 // Otherwise, it uses the paint's alpha 495 int color = p->getColor(); 496 if (((color >> 24) & 0xFF) == 255) { 497 color |= p->getAlpha() << 24; 498 } 499 500 drawColorRect(left, top, right, bottom, color, mode); 501} 502 503void OpenGLRenderer::drawColorRect(float left, float top, float right, float bottom, 504 int color, SkXfermode::Mode mode) { 505 const int alpha = (color >> 24) & 0xFF; 506 const bool blend = alpha < 255 || mode != SkXfermode::kSrcOver_Mode; 507 508 const GLfloat a = alpha / 255.0f; 509 const GLfloat r = ((color >> 16) & 0xFF) / 255.0f; 510 const GLfloat g = ((color >> 8) & 0xFF) / 255.0f; 511 const GLfloat b = ((color ) & 0xFF) / 255.0f; 512 513 if (blend) { 514 glEnable(GL_BLEND); 515 glBlendFunc(gBlends[mode].src, gBlends[mode].dst); 516 } 517 518 mModelView.loadTranslate(left, top, 0.0f); 519 mModelView.scale(right - left, bottom - top, 1.0f); 520 521 mDrawColorShader->use(&mOrthoMatrix[0], &mModelView.data[0], &mSnapshot->transform.data[0]); 522 523 const GLvoid* p = &gDrawColorVertices[0].position[0]; 524 525 glEnableVertexAttribArray(mDrawColorShader->position); 526 glVertexAttribPointer(mDrawColorShader->position, 2, GL_FLOAT, GL_FALSE, 527 gDrawColorVertexStride, p); 528 glVertexAttrib4f(mDrawColorShader->color, r, g, b, a); 529 530 glDrawArrays(GL_TRIANGLE_STRIP, 0, gDrawColorVertexCount); 531 532 glDisableVertexAttribArray(mDrawColorShader->position); 533 534 if (blend) { 535 glDisable(GL_BLEND); 536 } 537} 538 539void OpenGLRenderer::drawTextureRect(float left, float top, float right, float bottom, 540 GLuint texture, float alpha, SkXfermode::Mode mode, bool blend, bool isPremultiplied) { 541 mModelView.loadTranslate(left, top, 0.0f); 542 mModelView.scale(right - left, bottom - top, 1.0f); 543 544 mDrawTextureShader->use(&mOrthoMatrix[0], &mModelView.data[0], &mSnapshot->transform.data[0]); 545 546 if (blend || alpha < 1.0f || mode != SkXfermode::kSrcOver_Mode) { 547 GLenum sourceMode = gBlends[mode].src; 548 if (!isPremultiplied && sourceMode == GL_ONE) { 549 sourceMode = GL_SRC_ALPHA; 550 } 551 552 glEnable(GL_BLEND); 553 glBlendFunc(sourceMode, gBlends[mode].dst); 554 } 555 556 glBindTexture(GL_TEXTURE_2D, texture); 557 558 // TODO handle tiling and filtering here 559 560 glActiveTexture(GL_TEXTURE0); 561 glUniform1i(mDrawTextureShader->sampler, 0); 562 563 const GLvoid* p = &mDrawTextureVertices[0].position[0]; 564 const GLvoid* t = &mDrawTextureVertices[0].texture[0]; 565 566 glEnableVertexAttribArray(mDrawTextureShader->position); 567 glVertexAttribPointer(mDrawTextureShader->position, 2, GL_FLOAT, GL_FALSE, 568 gDrawTextureVertexStride, p); 569 570 glEnableVertexAttribArray(mDrawTextureShader->texCoords); 571 glVertexAttribPointer(mDrawTextureShader->texCoords, 2, GL_FLOAT, GL_FALSE, 572 gDrawTextureVertexStride, t); 573 574 glVertexAttrib4f(mDrawTextureShader->color, 1.0f, 1.0f, 1.0f, alpha); 575 576 glDrawArrays(GL_TRIANGLE_STRIP, 0, gDrawTextureVertexCount); 577 578 glDisableVertexAttribArray(mDrawTextureShader->position); 579 glDisableVertexAttribArray(mDrawTextureShader->texCoords); 580 581 glBindTexture(GL_TEXTURE_2D, 0); 582 glDisable(GL_BLEND); 583} 584 585void OpenGLRenderer::resetDrawTextureTexCoords(float u1, float v1, float u2, float v2) { 586 mDrawTextureVertices[0].texture[0] = u1; 587 mDrawTextureVertices[0].texture[1] = v1; 588 mDrawTextureVertices[1].texture[0] = u2; 589 mDrawTextureVertices[1].texture[1] = v1; 590 mDrawTextureVertices[2].texture[0] = u1; 591 mDrawTextureVertices[2].texture[1] = v2; 592 mDrawTextureVertices[3].texture[0] = u2; 593 mDrawTextureVertices[3].texture[1] = v2; 594} 595 596void OpenGLRenderer::getAlphaAndMode(const SkPaint* paint, int* alpha, SkXfermode::Mode* mode) { 597 if (paint) { 598 const bool isMode = SkXfermode::IsMode(paint->getXfermode(), mode); 599 if (!isMode) { 600 // Assume SRC_OVER 601 *mode = SkXfermode::kSrcOver_Mode; 602 } 603 604 // Skia draws using the color's alpha channel if < 255 605 // Otherwise, it uses the paint's alpha 606 int color = paint->getColor(); 607 *alpha = (color >> 24) & 0xFF; 608 if (*alpha == 255) { 609 *alpha = paint->getAlpha(); 610 } 611 } else { 612 *mode = SkXfermode::kSrcOver_Mode; 613 *alpha = 255; 614 } 615} 616 617}; // namespace uirenderer 618}; // namespace android 619