path: root/chrome/browser/renderer_host/backing_store_x.cc

// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "chrome/browser/renderer_host/backing_store.h"

#include <stdlib.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#if defined(TOOLKIT_GTK)
#include <cairo-xlib.h>
#include <gtk/gtk.h>
#endif

#include <algorithm>
#include <utility>

#include "base/compiler_specific.h"
#include "base/histogram.h"
#include "base/logging.h"
#include "base/time.h"
#include "chrome/common/transport_dib.h"
#include "chrome/common/x11_util.h"
#include "chrome/common/x11_util_internal.h"
#include "third_party/skia/include/core/SkBitmap.h"

// X Backing Stores:
//
// Unlike Windows, where the backing store is kept in heap memory, we keep our
// backing store in the X server, as a pixmap. Thus expose events just require
// instructing the X server to copy from the backing store to the window.
//
// The backing store is in the same format as the visual which our main window
// is using. Bitmaps from the renderer are uploaded to the X server, either via
// shared memory or over the wire, and XRENDER is used to convert them to the
// correct format for the backing store.

// Destroys the image and the associated shared memory structures. This is a
// helper function for code using shared memory.
static void DestroySharedImage(Display* display,
                               XImage* image,
                               XShmSegmentInfo* shminfo) {
  XShmDetach(display, shminfo);
  XDestroyImage(image);
  shmdt(shminfo->shmaddr);
}

BackingStore::BackingStore(RenderWidgetHost* widget,
                           const gfx::Size& size,
                           void* visual,
                           int depth)
    : render_widget_host_(widget),
      size_(size),
      display_(x11_util::GetXDisplay()),
      use_shared_memory_(x11_util::QuerySharedMemorySupport(display_)),
      use_render_(x11_util::QueryRenderSupport(display_)),
      visual_(visual),
      visual_depth_(depth),
      root_window_(x11_util::GetX11RootWindow()) {
  COMPILE_ASSERT(__BYTE_ORDER == __LITTLE_ENDIAN, assumes_little_endian);

  pixmap_ = XCreatePixmap(display_, root_window_,
                          size.width(), size.height(), depth);

  if (use_render_) {
    picture_ = XRenderCreatePicture(
        display_, pixmap_,
        x11_util::GetRenderVisualFormat(display_,
                                        static_cast<Visual*>(visual)),
                                        0, NULL);
  } else {
    picture_ = 0;
    pixmap_bpp_ = x11_util::BitsPerPixelForPixmapDepth(display_, depth);
  }

  pixmap_gc_ = XCreateGC(display_, pixmap_, 0, NULL);
}

BackingStore::BackingStore(RenderWidgetHost* widget, const gfx::Size& size)
    : render_widget_host_(widget),
      size_(size),
      display_(NULL),
      use_shared_memory_(false),
      use_render_(false),
      visual_(NULL),
      visual_depth_(-1),
      root_window_(0) {
}

BackingStore::~BackingStore() {
  // In unit tests, display_ may be NULL.
  if (!display_)
    return;

  XRenderFreePicture(display_, picture_);
  XFreePixmap(display_, pixmap_);
  XFreeGC(display_, static_cast<GC>(pixmap_gc_));
}

size_t BackingStore::MemorySize() {
  if (!use_render_)
    return size_.GetArea() * (pixmap_bpp_ / 8);
  else
    return size_.GetArea() * 4;
}

void BackingStore::PaintRectWithoutXrender(TransportDIB* bitmap,
                                           const gfx::Rect &bitmap_rect) {
  const int width = bitmap_rect.width();
  const int height = bitmap_rect.height();
  Pixmap pixmap = XCreatePixmap(display_, root_window_, width, height,
                                visual_depth_);

  XImage image;
  memset(&image, 0, sizeof(image));

  image.width = width;
  image.height = height;
  image.format = ZPixmap;
  image.byte_order = LSBFirst;
  image.bitmap_unit = 8;
  image.bitmap_bit_order = LSBFirst;
  image.depth = visual_depth_;
  image.bits_per_pixel = pixmap_bpp_;
  image.bytes_per_line = width * pixmap_bpp_ / 8;

  if (pixmap_bpp_ == 32) {
    image.red_mask = 0xff0000;
    image.green_mask = 0xff00;
    image.blue_mask = 0xff;

    // If the X server depth is already 32-bits and the color masks match,
    // then our job is easy.
    Visual* vis = static_cast<Visual*>(visual_);
    if (image.red_mask == vis->red_mask &&
        image.green_mask == vis->green_mask &&
        image.blue_mask == vis->blue_mask) {
      image.data = static_cast<char*>(bitmap->memory());
      XPutImage(display_, pixmap, static_cast<GC>(pixmap_gc_), &image,
                0, 0 /* source x, y */, 0, 0 /* dest x, y */,
                width, height);
    } else {
      // Otherwise, we need to shuffle the colors around. Assume red and blue
      // need to be swapped.
      //
      // It's possible to use some fancy SSE tricks here, but since this is the
      // slow path anyway, we do it slowly.

      uint8_t* bitmap32 = static_cast<uint8_t*>(malloc(4 * width * height));
      if (!bitmap32)
        return;
      uint8_t* const orig_bitmap32 = bitmap32;
      const uint32_t* bitmap_in =
          static_cast<const uint32_t*>(bitmap->memory());
      for (int y = 0; y < height; ++y) {
        for (int x = 0; x < width; ++x) {
          const uint32_t pixel = *(bitmap_in++);
          bitmap32[0] = (pixel >> 16) & 0xff;  // Red
          bitmap32[1] = (pixel >> 8) & 0xff;   // Green
          bitmap32[2] = pixel & 0xff;          // Blue
          bitmap32[3] = (pixel >> 24) & 0xff;  // Alpha
          bitmap32 += 4;
        }
      }
      image.data = reinterpret_cast<char*>(orig_bitmap32);
      XPutImage(display_, pixmap, static_cast<GC>(pixmap_gc_), &image,
                0, 0 /* source x, y */, 0, 0 /* dest x, y */,
                width, height);
      free(orig_bitmap32);
    }
  } else if (pixmap_bpp_ == 16) {
    // Some folks have VNC setups which still use 16-bit visuals and VNC
    // doesn't include Xrender.

    uint16_t* bitmap16 = static_cast<uint16_t*>(malloc(2 * width * height));
    if (!bitmap16)
      return;
    uint16_t* const orig_bitmap16 = bitmap16;
    const uint32_t* bitmap_in = static_cast<const uint32_t*>(bitmap->memory());
    for (int y = 0; y < height; ++y) {
      for (int x = 0; x < width; ++x) {
        const uint32_t pixel = *(bitmap_in++);
        uint16_t out_pixel = ((pixel >> 8) & 0xf800) |
                             ((pixel >> 5) & 0x07e0) |
                             ((pixel >> 3) & 0x001f);
        *(bitmap16++) = out_pixel;
      }
    }

    image.data = reinterpret_cast<char*>(orig_bitmap16);
    image.red_mask = 0xf800;
    image.green_mask = 0x07e0;
    image.blue_mask = 0x001f;

    XPutImage(display_, pixmap, static_cast<GC>(pixmap_gc_), &image,
              0, 0 /* source x, y */, 0, 0 /* dest x, y */,
              width, height);
    free(orig_bitmap16);
  } else {
    CHECK(false) << "Sorry, we don't support your visual depth without "
                    "Xrender support (depth:" << visual_depth_
                 << " bpp:" << pixmap_bpp_ << ")";
  }

  XCopyArea(display_, pixmap /* source */, pixmap_ /* target */,
            static_cast<GC>(pixmap_gc_),
            0, 0 /* source x, y */, bitmap_rect.width(), bitmap_rect.height(),
            bitmap_rect.x(), bitmap_rect.y() /* dest x, y */);

  XFreePixmap(display_, pixmap);
}

void BackingStore::PaintRect(base::ProcessHandle process,
                             TransportDIB* bitmap,
                             const gfx::Rect& bitmap_rect) {
  if (!display_)
    return;

  if (bitmap_rect.IsEmpty())
    return;

  const int width = bitmap_rect.width();
  const int height = bitmap_rect.height();
  // Assume that somewhere along the line, someone will do width * height * 4
  // with signed numbers. If the maximum value is 2**31, then 2**31 / 4 =
  // 2**29 and floor(sqrt(2**29)) = 23170.
  if (width > 23170 || height > 23170)
    return;

  if (!use_render_)
    return PaintRectWithoutXrender(bitmap, bitmap_rect);

  Picture picture;
  Pixmap pixmap;

  if (use_shared_memory_) {
    const XID shmseg = bitmap->MapToX(display_);

    XShmSegmentInfo shminfo;
    memset(&shminfo, 0, sizeof(shminfo));
    shminfo.shmseg = shmseg;

    // The NULL in the following is the |data| pointer: this is an artifact of
    // Xlib trying to be helpful, rather than just exposing the X protocol. It
    // assumes that we have the shared memory segment mapped into our memory,
    // which we don't, and it's trying to calculate an offset by taking the
    // difference between the |data| pointer and the address of the mapping in
    // |shminfo|. Since both are NULL, the offset will be calculated to be 0,
    // which is correct for us.
    pixmap = XShmCreatePixmap(display_, root_window_, NULL, &shminfo, width,
                              height, 32);
  } else {
    // No shared memory support, we have to copy the bitmap contents to the X
    // server. Xlib wraps the underlying PutImage call behind several layers of
    // functions which try to convert the image into the format which the X
    // server expects. The following values hopefully disable all conversions.
    XImage image;
    memset(&image, 0, sizeof(image));

    image.width = width;
    image.height = height;
    image.depth = 32;
    image.bits_per_pixel = 32;
    image.format = ZPixmap;
    image.byte_order = LSBFirst;
    image.bitmap_unit = 8;
    image.bitmap_bit_order = LSBFirst;
    image.bytes_per_line = width * 4;
    image.red_mask = 0xff;
    image.green_mask = 0xff00;
    image.blue_mask = 0xff0000;
    image.data = static_cast<char*>(bitmap->memory());

    pixmap = XCreatePixmap(display_, root_window_, width, height, 32);
    GC gc = XCreateGC(display_, pixmap, 0, NULL);
    XPutImage(display_, pixmap, gc, &image,
              0, 0 /* source x, y */, 0, 0 /* dest x, y */,
              width, height);
    XFreeGC(display_, gc);
  }

  picture = x11_util::CreatePictureFromSkiaPixmap(display_, pixmap);
  XRenderComposite(display_, PictOpSrc, picture /* source */, 0 /* mask */,
                   picture_ /* dest */, 0, 0 /* source x, y */,
                   0, 0 /* mask x, y */,
                   bitmap_rect.x(), bitmap_rect.y() /* target x, y */,
                   width, height);

  // In the case of shared memory, we wait for the composite to complete so that
  // we are sure that the X server has finished reading.
  if (use_shared_memory_)
    XSync(display_, False);

  XRenderFreePicture(display_, picture);
  XFreePixmap(display_, pixmap);
}

void BackingStore::ScrollRect(base::ProcessHandle process,
                              TransportDIB* bitmap,
                              const gfx::Rect& bitmap_rect,
                              int dx, int dy,
                              const gfx::Rect& clip_rect,
                              const gfx::Size& view_size) {
  if (!display_)
    return;

  // We only support scrolling in one direction at a time.
  DCHECK(dx == 0 || dy == 0);

  if (dy) {
    // Positive values of |dy| scroll up
    if (abs(dy) < clip_rect.height()) {
      XCopyArea(display_, pixmap_, pixmap_, static_cast<GC>(pixmap_gc_),
                clip_rect.x() /* source x */,
                std::max(clip_rect.y(), clip_rect.y() - dy),
                clip_rect.width(),
                clip_rect.height() - abs(dy),
                clip_rect.x() /* dest x */,
                std::max(clip_rect.y(), clip_rect.y() + dy) /* dest y */);
    }
  } else if (dx) {
    // Positive values of |dx| scroll right
    if (abs(dx) < clip_rect.width()) {
      XCopyArea(display_, pixmap_, pixmap_, static_cast<GC>(pixmap_gc_),
                std::max(clip_rect.x(), clip_rect.x() - dx),
                clip_rect.y() /* source y */,
                clip_rect.width() - abs(dx),
                clip_rect.height(),
                std::max(clip_rect.x(), clip_rect.x() + dx) /* dest x */,
                clip_rect.y() /* dest x */);
    }
  }

  PaintRect(process, bitmap, bitmap_rect);
}

void BackingStore::ShowRect(const gfx::Rect& rect, XID target) {
  XCopyArea(display_, pixmap_, target, static_cast<GC>(pixmap_gc_),
            rect.x(), rect.y(), rect.width(), rect.height(),
            rect.x(), rect.y());
}

#if defined(TOOLKIT_GTK)
void BackingStore::PaintToRect(const gfx::Rect& rect, GdkDrawable* target) {
  cairo_surface_t* surface = cairo_xlib_surface_create(
      display_, pixmap_, static_cast<Visual*>(visual_),
      size_.width(), size_.height());
  cairo_t* cr = gdk_cairo_create(target);

  cairo_translate(cr, rect.x(), rect.y());
  double x_scale = static_cast<double>(rect.width()) / size_.width();
  double y_scale = static_cast<double>(rect.height()) / size_.height();
  cairo_scale(cr, x_scale, y_scale);

  cairo_pattern_t* pattern = cairo_pattern_create_for_surface(surface);
  cairo_pattern_set_filter(pattern, CAIRO_FILTER_BEST);
  cairo_set_source(cr, pattern);
  cairo_pattern_destroy(pattern);

  cairo_identity_matrix(cr);

  cairo_rectangle(cr, rect.x(), rect.y(), rect.width(), rect.height());
  cairo_fill(cr);
  cairo_destroy(cr);
}
#endif

SkBitmap BackingStore::PaintRectToBitmap(const gfx::Rect& rect) {
  base::TimeTicks begin_time = base::TimeTicks::Now();
  const int width = std::min(size_.width(), rect.width());
  const int height = std::min(size_.height(), rect.height());

  XImage* image;
  XShmSegmentInfo shminfo;  // Used only when shared memory is enabled.
  if (use_shared_memory_) {
    // Use shared memory for faster copies when it's available.
    Visual* visual = static_cast<Visual*>(visual_);
    memset(&shminfo, 0, sizeof(shminfo));
    image = XShmCreateImage(display_, visual, 32,
                            ZPixmap, NULL, &shminfo, width, height);

    // Create the shared memory segment for the image and map it.
    shminfo.shmid = shmget(IPC_PRIVATE, image->bytes_per_line * image->height,
                           IPC_CREAT|0666);
    if (shminfo.shmid == -1) {
      XDestroyImage(image);
      return SkBitmap();
    }

    void* mapped_memory = shmat(shminfo.shmid, NULL, SHM_RDONLY);
    shmctl(shminfo.shmid, IPC_RMID, 0);
    if (mapped_memory == (void*)-1) {
      XDestroyImage(image);
      return SkBitmap();
    }
    shminfo.shmaddr = image->data = static_cast<char*>(mapped_memory);

    if (!XShmAttach(display_, &shminfo) ||
        !XShmGetImage(display_, pixmap_, image, rect.x(), rect.y(),
                      AllPlanes)) {
      DestroySharedImage(display_, image, &shminfo);
      return SkBitmap();
    }
  } else {
    // Non-shared memory case just copy the image from the server.
    image = XGetImage(display_, pixmap_,
                      rect.x(), rect.y(), width, height,
                      AllPlanes, ZPixmap);
  }

  // TODO(jhawkins): Need to convert the image data if the image bits per pixel
  // is not 32.
  if (image->bits_per_pixel != 32) {
    if (use_shared_memory_)
      DestroySharedImage(display_, image, &shminfo);
    else
      XFree(image);
    return SkBitmap();
  }

  // Create a bitmap to put the results into, being careful to use the stride
  // from the image rather than the width for the size.
  SkBitmap bitmap;
  bitmap.setConfig(SkBitmap::kARGB_8888_Config, width, height,
                   image->bytes_per_line);
  bitmap.allocPixels();
  unsigned char* bitmap_data =
      reinterpret_cast<unsigned char*>(bitmap.getAddr32(0, 0));
  memcpy(bitmap_data, image->data, image->bytes_per_line * height);

  if (use_shared_memory_)
    DestroySharedImage(display_, image, &shminfo);
  else
    XFree(image);

  HISTOGRAM_TIMES("BackingStore.RetrievalFromX",
                  base::TimeTicks::Now() - begin_time);
  return bitmap;
}