path: root/ppapi/shared_impl/private/ppb_font_shared.cc

// Copyright (c) 2011 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 "ppapi/shared_impl/private/ppb_font_shared.h"

#include "base/debug/trace_event.h"
#include "base/string_util.h"
#include "base/utf_string_conversions.h"
#include "ppapi/c/dev/ppb_font_dev.h"
#include "ppapi/shared_impl/ppapi_preferences.h"
#include "ppapi/shared_impl/var.h"
#include "ppapi/thunk/enter.h"
#include "ppapi/thunk/ppb_image_data_api.h"
#include "ppapi/thunk/thunk.h"
#include "skia/ext/platform_canvas.h"
#include "third_party/skia/include/core/SkRect.h"
#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebCanvas.h"
#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebFloatPoint.h"
#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebFloatRect.h"
#include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebRect.h"
#include "third_party/WebKit/Source/WebKit/chromium/public/WebFont.h"
#include "third_party/WebKit/Source/WebKit/chromium/public/WebFontDescription.h"
#include "third_party/WebKit/Source/WebKit/chromium/public/WebTextRun.h"

using ppapi::StringVar;
using ppapi::thunk::EnterResource;
using ppapi::thunk::EnterResourceNoLock;
using ppapi::thunk::PPB_ImageData_API;
using ppapi::WebKitForwarding;
using WebKit::WebFloatPoint;
using WebKit::WebFloatRect;
using WebKit::WebFont;
using WebKit::WebFontDescription;
using WebKit::WebRect;
using WebKit::WebTextRun;
using WebKit::WebCanvas;

namespace ppapi {

namespace {

// Converts the given PP_TextRun to a TextRun, returning true on success.
// False means the input was invalid.
bool PPTextRunToTextRun(const PP_TextRun_Dev* run,
                        WebKitForwarding::Font::TextRun* output) {
  StringVar* text_string = StringVar::FromPPVar(run->text);
  if (!text_string)
    return false;

  output->text = text_string->value();
  output->rtl = run->rtl == PP_TRUE ? true : false;
  output->override_direction =
      run->override_direction == PP_TRUE ? true : false;
  return true;
}

// The PP_* version lacks "None", so is just one value shifted from the
// WebFontDescription version. These values are checked in
// PPFontDescToWebFontDesc to make sure the conversion is correct. This is a
// macro so it can also be used in the COMPILE_ASSERTS.
#define PP_FONTFAMILY_TO_WEB_FONTFAMILY(f) \
  static_cast<WebFontDescription::GenericFamily>(f + 1)

// Assumes the given PP_FontDescription has been validated.
WebFontDescription PPFontDescToWebFontDesc(const PP_FontDescription_Dev& font,
                                           const std::string& face,
                                           const ::ppapi::Preferences& prefs) {
  // Verify that the enums match so we can just static cast.
  COMPILE_ASSERT(static_cast<int>(WebFontDescription::Weight100) ==
                 static_cast<int>(PP_FONTWEIGHT_100),
                 FontWeight100);
  COMPILE_ASSERT(static_cast<int>(WebFontDescription::Weight900) ==
                 static_cast<int>(PP_FONTWEIGHT_900),
                 FontWeight900);
  COMPILE_ASSERT(WebFontDescription::GenericFamilyStandard ==
                 PP_FONTFAMILY_TO_WEB_FONTFAMILY(PP_FONTFAMILY_DEFAULT),
                 StandardFamily);
  COMPILE_ASSERT(WebFontDescription::GenericFamilySerif ==
                 PP_FONTFAMILY_TO_WEB_FONTFAMILY(PP_FONTFAMILY_SERIF),
                 SerifFamily);
  COMPILE_ASSERT(WebFontDescription::GenericFamilySansSerif ==
                 PP_FONTFAMILY_TO_WEB_FONTFAMILY(PP_FONTFAMILY_SANSSERIF),
                 SansSerifFamily);
  COMPILE_ASSERT(WebFontDescription::GenericFamilyMonospace ==
                 PP_FONTFAMILY_TO_WEB_FONTFAMILY(PP_FONTFAMILY_MONOSPACE),
                 MonospaceFamily);

  WebFontDescription result;
  string16 resolved_family;
  if (face.empty()) {
    // Resolve the generic family.
    switch (font.family) {
      case PP_FONTFAMILY_SERIF:
        resolved_family = prefs.serif_font_family;
        break;
      case PP_FONTFAMILY_SANSSERIF:
        resolved_family = prefs.sans_serif_font_family;
        break;
      case PP_FONTFAMILY_MONOSPACE:
        resolved_family = prefs.fixed_font_family;
        break;
      case PP_FONTFAMILY_DEFAULT:
      default:
        resolved_family = prefs.standard_font_family;
        break;
    }
  } else {
    // Use the exact font.
    resolved_family = UTF8ToUTF16(face);
  }
  result.family = resolved_family;

  result.genericFamily = PP_FONTFAMILY_TO_WEB_FONTFAMILY(font.family);

  if (font.size == 0) {
    // Resolve the default font size, using the resolved family to see if
    // we should use the fixed or regular font size. It's difficult at this
    // level to detect if the requested font is fixed width, so we only apply
    // the alternate font size to the default fixed font family.
    if (StringToLowerASCII(resolved_family) ==
        StringToLowerASCII(prefs.fixed_font_family))
      result.size = static_cast<float>(prefs.default_fixed_font_size);
    else
      result.size = static_cast<float>(prefs.default_font_size);
  } else {
    // Use the exact size.
    result.size = static_cast<float>(font.size);
  }

  result.italic = font.italic != PP_FALSE;
  result.smallCaps = font.small_caps != PP_FALSE;
  result.weight = static_cast<WebFontDescription::Weight>(font.weight);
  result.letterSpacing = static_cast<short>(font.letter_spacing);
  result.wordSpacing = static_cast<short>(font.word_spacing);
  return result;
}

WebTextRun TextRunToWebTextRun(const WebKitForwarding::Font::TextRun& run) {
  return WebTextRun(UTF8ToUTF16(run.text),
                    run.rtl != PP_FALSE,
                    run.override_direction != PP_FALSE);
}

// FontImpl --------------------------------------------------------------------

class FontImpl : public WebKitForwarding::Font {
 public:
  FontImpl(const PP_FontDescription_Dev& desc,
           const std::string& desc_face,
           const ::ppapi::Preferences& prefs);
  virtual ~FontImpl();

  virtual void Describe(PP_FontDescription_Dev* description,
                        std::string* face,
                        PP_FontMetrics_Dev* metrics,
                        PP_Bool* result) OVERRIDE;
  virtual void DrawTextAt(const DrawTextParams& params) OVERRIDE;
  virtual void MeasureText(const TextRun& text,
                           int32_t* result) OVERRIDE;
  virtual void CharacterOffsetForPixel(const TextRun& text,
                                       int32_t pixel_position,
                                       uint32_t* result) OVERRIDE;
  virtual void PixelOffsetForCharacter(const TextRun& text,
                                       uint32_t char_offset,
                                       int32_t* result) OVERRIDE;

 private:
  scoped_ptr<WebFont> font_;

  DISALLOW_COPY_AND_ASSIGN(FontImpl);
};

FontImpl::FontImpl(const PP_FontDescription_Dev& desc,
                   const std::string& desc_face,
                   const ::ppapi::Preferences& prefs) {
  WebFontDescription web_font_desc = PPFontDescToWebFontDesc(desc, desc_face,
                                                             prefs);
  font_.reset(WebFont::create(web_font_desc));
}

FontImpl::~FontImpl() {
}

void FontImpl::Describe(PP_FontDescription_Dev* description,
                        std::string* face,
                        PP_FontMetrics_Dev* metrics,
                        PP_Bool* result) {
  TRACE_EVENT0("ppapi WebKit thread", "FontImpl::Describe");
  if (description->face.type != PP_VARTYPE_UNDEFINED) {
    *result = PP_FALSE;
  } else {
    WebFontDescription web_desc = font_->fontDescription();

    // While converting the other way in PPFontDescToWebFontDesc we validated
    // that the enums can be casted.
    description->face = PP_MakeUndefined();
    description->family =
        static_cast<PP_FontFamily_Dev>(web_desc.genericFamily);
    description->size = static_cast<uint32_t>(web_desc.size);
    description->weight = static_cast<PP_FontWeight_Dev>(web_desc.weight);
    description->italic = web_desc.italic ? PP_TRUE : PP_FALSE;
    description->small_caps = web_desc.smallCaps ? PP_TRUE : PP_FALSE;
    description->letter_spacing = static_cast<int32_t>(web_desc.letterSpacing);
    description->word_spacing = static_cast<int32_t>(web_desc.wordSpacing);

    *face = UTF16ToUTF8(web_desc.family);

    metrics->height = font_->height();
    metrics->ascent = font_->ascent();
    metrics->descent = font_->descent();
    metrics->line_spacing = font_->lineSpacing();
    metrics->x_height = static_cast<int32_t>(font_->xHeight());

    *result = PP_TRUE;
  }
}

void FontImpl::DrawTextAt(const DrawTextParams& params) {
  TRACE_EVENT0("ppapi WebKit thread", "FontImpl::DrawTextAt");
  WebTextRun run = TextRunToWebTextRun(params.text);

  // Convert position and clip.
  WebFloatPoint web_position(static_cast<float>(params.position->x),
                             static_cast<float>(params.position->y));
  WebRect web_clip;
  if (!params.clip) {
    // Use entire canvas. SkCanvas doesn't have a size on it, so we just use
    // the current clip bounds.
    SkRect skclip;
    params.destination->getClipBounds(&skclip);
    web_clip = WebRect(skclip.fLeft, skclip.fTop, skclip.fRight - skclip.fLeft,
                       skclip.fBottom - skclip.fTop);
  } else {
    web_clip = WebRect(params.clip->point.x, params.clip->point.y,
                       params.clip->size.width, params.clip->size.height);
  }

#if WEBKIT_USING_SKIA
  WebCanvas* canvas = params.destination;
#elif WEBKIT_USING_CG
  WebCanvas* canvas = skia::GetBitmapContext(skia::GetTopDevice(*destination));
#else
  NOTIMPLEMENTED();
  return;
#endif
  font_->drawText(canvas, run, web_position, params.color, web_clip,
                  params.image_data_is_opaque == PP_TRUE);
}

void FontImpl::MeasureText(const TextRun& text, int32_t* result) {
  TRACE_EVENT0("ppapi WebKit thread", "FontImpl::MeasureText");
  *result = font_->calculateWidth(TextRunToWebTextRun(text));
}

void FontImpl::CharacterOffsetForPixel(const TextRun& text,
                                       int32_t pixel_position,
                                       uint32_t* result) {
  TRACE_EVENT0("ppapi WebKit thread", "FontImpl::CharacterOffsetForPixel");
  *result = static_cast<uint32_t>(font_->offsetForPosition(
      TextRunToWebTextRun(text), static_cast<float>(pixel_position)));
}

void FontImpl::PixelOffsetForCharacter(const TextRun& text,
                                       uint32_t char_offset,
                                       int32_t* result) {
  TRACE_EVENT0("ppapi WebKit thread", "FontImpl::PixelOffsetForCharacter");
  WebTextRun run = TextRunToWebTextRun(text);
  if (char_offset >= run.text.length()) {
    *result = -1;
  } else {
    WebFloatRect rect = font_->selectionRectForText(
        run, WebFloatPoint(0.0f, 0.0f), font_->height(), 0, char_offset);
    *result = static_cast<int>(rect.width);
  }
}

}  // namespace

// static
bool PPB_Font_Shared::IsPPFontDescriptionValid(
    const PP_FontDescription_Dev& desc) {
  // Check validity of string. We can't check the actual text since we could
  // be on the wrong thread and don't know if we're in the plugin or the host.
  if (desc.face.type != PP_VARTYPE_STRING &&
      desc.face.type != PP_VARTYPE_UNDEFINED)
    return false;

  // Check enum ranges.
  if (static_cast<int>(desc.family) < PP_FONTFAMILY_DEFAULT ||
      static_cast<int>(desc.family) > PP_FONTFAMILY_MONOSPACE)
    return false;
  if (static_cast<int>(desc.weight) < PP_FONTWEIGHT_100 ||
      static_cast<int>(desc.weight) > PP_FONTWEIGHT_900)
    return false;

  // Check for excessive sizes which may cause layout to get confused.
  if (desc.size > 200)
    return false;

  return true;
}

// static
PP_Resource PPB_Font_Shared::CreateAsImpl(
    PP_Instance instance,
    const PP_FontDescription_Dev& description,
    const ::ppapi::Preferences& prefs) {
  if (!::ppapi::PPB_Font_Shared::IsPPFontDescriptionValid(description))
    return 0;
  return (new PPB_Font_Shared(instance, description, prefs))->GetReference();
}

// static
PP_Resource PPB_Font_Shared::CreateAsProxy(
    PP_Instance instance,
    const PP_FontDescription_Dev& description,
    const ::ppapi::Preferences& prefs) {
  return CreateAsImpl(instance, description, prefs);
}

PPB_Font_Shared::PPB_Font_Shared(PP_Instance pp_instance,
                                 const PP_FontDescription_Dev& desc,
                                 const ::ppapi::Preferences& prefs)
    : Resource(pp_instance) {
  StringVar* face_name = StringVar::FromPPVar(desc.face);

  font_impl_.reset(new FontImpl(
      desc, face_name ? face_name->value() : std::string(), prefs));
}

PPB_Font_Shared::~PPB_Font_Shared() {
}

::ppapi::thunk::PPB_Font_API* PPB_Font_Shared::AsPPB_Font_API() {
  return this;
}

PP_Bool PPB_Font_Shared::Describe(PP_FontDescription_Dev* description,
                                  PP_FontMetrics_Dev* metrics) {
  std::string face;
  PP_Bool result = PP_FALSE;
  font_impl_->Describe(description, &face, metrics, &result);
  if (!result)
    return PP_FALSE;

  // Convert the string.
  description->face = StringVar::StringToPPVar(face);
  return PP_TRUE;
}

PP_Bool PPB_Font_Shared::DrawTextAt(PP_Resource image_data,
                                    const PP_TextRun_Dev* text,
                                    const PP_Point* position,
                                    uint32_t color,
                                    const PP_Rect* clip,
                                    PP_Bool image_data_is_opaque) {
  PP_Bool result = PP_FALSE;
  // Get and map the image data we're painting to.
  EnterResource<PPB_ImageData_API> enter(image_data, true);
  if (enter.failed())
    return result;

  // TODO(ananta)
  // We need to remove dependency on skia from this layer.
  PPB_ImageData_API* image = static_cast<PPB_ImageData_API*>(
      enter.object());
  skia::PlatformCanvas* canvas = image->GetPlatformCanvas();
  bool needs_unmapping = false;
  if (!canvas) {
    needs_unmapping = true;
    image->Map();
    canvas = image->GetPlatformCanvas();
    if (!canvas)
      return result;  // Failure mapping.
  }

  WebKitForwarding::Font::TextRun run;
  if (PPTextRunToTextRun(text, &run)) {
    font_impl_->DrawTextAt(WebKitForwarding::Font::DrawTextParams(
        canvas, run, position, color, clip, image_data_is_opaque));
    result = PP_TRUE;
  }

  if (needs_unmapping)
    image->Unmap();
  return result;
}

int32_t PPB_Font_Shared::MeasureText(const PP_TextRun_Dev* text) {
  int32_t result = -1;
  WebKitForwarding::Font::TextRun run;
  if (PPTextRunToTextRun(text, &run))
    font_impl_->MeasureText(run, &result);
  return result;
}

uint32_t PPB_Font_Shared::CharacterOffsetForPixel(const PP_TextRun_Dev* text,
                                                  int32_t pixel_position) {
  uint32_t result = -1;
  WebKitForwarding::Font::TextRun run;
  if (PPTextRunToTextRun(text, &run)) {
    font_impl_->CharacterOffsetForPixel(run, pixel_position, &result);
  }
  return result;
}

int32_t PPB_Font_Shared::PixelOffsetForCharacter(const PP_TextRun_Dev* text,
                                                uint32_t char_offset) {
  int32_t result = -1;
  WebKitForwarding::Font::TextRun run;
  if (PPTextRunToTextRun(text, &run)) {
    font_impl_->PixelOffsetForCharacter(run, char_offset, &result);
  }
  return result;
}

}  // namespace ppapi