blob: 6d7275d2f434ededc6e5dcede4e274c65a7429cf [file] [log] [blame]
// Copyright (c) 2012 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 "ui/gfx/platform_font_win.h"
#include <algorithm>
#include <dwrite.h>
#include <math.h>
#include <windows.h>
#include "base/debug/alias.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/strings/string16.h"
#include "base/strings/string_util.h"
#include "base/strings/sys_string_conversions.h"
#include "base/strings/utf_string_conversions.h"
#include "base/win/scoped_comptr.h"
#include "base/win/scoped_gdi_object.h"
#include "base/win/scoped_hdc.h"
#include "base/win/scoped_select_object.h"
#include "base/win/win_util.h"
#include "third_party/skia/include/core/SkTypeface.h"
#include "ui/gfx/canvas.h"
#include "ui/gfx/font.h"
#include "ui/gfx/font_render_params.h"
#include "ui/gfx/win/scoped_set_map_mode.h"
namespace {
// If the tmWeight field of a TEXTMETRIC structure has a value >= this, the
// font is bold.
const int kTextMetricWeightBold = 700;
// Returns the minimum font size, using the minimum size callback, if set.
int GetMinimumFontSize() {
int min_font_size = 0;
if (gfx::PlatformFontWin::get_minimum_font_size_callback)
min_font_size = gfx::PlatformFontWin::get_minimum_font_size_callback();
return min_font_size;
}
// Returns either minimum font allowed for a current locale or
// lf_height + size_delta value.
int AdjustFontSize(int lf_height, int size_delta) {
if (lf_height < 0) {
lf_height -= size_delta;
} else {
lf_height += size_delta;
}
const int min_font_size = GetMinimumFontSize();
// Make sure lf_height is not smaller than allowed min font size for current
// locale.
if (abs(lf_height) < min_font_size) {
return lf_height < 0 ? -min_font_size : min_font_size;
} else {
return lf_height;
}
}
// Sets style properties on |font_info| based on |font_style|.
void SetLogFontStyle(int font_style, LOGFONT* font_info) {
font_info->lfUnderline = (font_style & gfx::Font::UNDERLINE) != 0;
font_info->lfItalic = (font_style & gfx::Font::ITALIC) != 0;
font_info->lfWeight = (font_style & gfx::Font::BOLD) ? FW_BOLD : FW_NORMAL;
}
// Returns the family name for the |IDWriteFont| interface passed in.
// The family name is returned in the |family_name_ret| parameter.
// Returns S_OK on success.
// TODO(ananta)
// Remove the CHECKs in this function once this stabilizes on the field.
HRESULT GetFamilyNameFromDirectWriteFont(IDWriteFont* dwrite_font,
base::string16* family_name_ret) {
base::win::ScopedComPtr<IDWriteFontFamily> font_family;
HRESULT hr = dwrite_font->GetFontFamily(font_family.Receive());
if (FAILED(hr))
CHECK(false);
base::win::ScopedComPtr<IDWriteLocalizedStrings> family_name;
hr = font_family->GetFamilyNames(family_name.Receive());
if (FAILED(hr))
CHECK(false);
// TODO(ananta)
// Add support for retrieving the family for the current locale.
wchar_t family_name_for_locale[MAX_PATH] = {0};
hr = family_name->GetString(0,
family_name_for_locale,
arraysize(family_name_for_locale));
if (FAILED(hr))
CHECK(false);
*family_name_ret = family_name_for_locale;
return hr;
}
// Uses the GDI interop functionality exposed by DirectWrite to find a
// matching DirectWrite font for the LOGFONT passed in. If we fail to
// find a direct match then we try the DirectWrite font substitution
// route to find a match.
// The contents of the LOGFONT pointer |font_info| may be modified on
// return.
HRESULT FindDirectWriteFontForLOGFONT(IDWriteFactory* factory,
LOGFONT* font_info,
IDWriteFont** dwrite_font) {
base::win::ScopedComPtr<IDWriteGdiInterop> gdi_interop;
HRESULT hr = factory->GetGdiInterop(gdi_interop.Receive());
if (FAILED(hr)) {
CHECK(false);
return hr;
}
hr = gdi_interop->CreateFontFromLOGFONT(font_info, dwrite_font);
if (SUCCEEDED(hr))
return hr;
base::win::ScopedComPtr<IDWriteFontCollection> font_collection;
hr = factory->GetSystemFontCollection(font_collection.Receive());
if (FAILED(hr)) {
CHECK(false);
return hr;
}
// We try to find a matching font by triggering DirectWrite to substitute the
// font passed in with a matching font (FontSubstitutes registry key)
// If this succeeds we return the matched font.
base::win::ScopedGDIObject<HFONT> font(::CreateFontIndirect(font_info));
base::win::ScopedGetDC screen_dc(NULL);
base::win::ScopedSelectObject scoped_font(screen_dc, font);
base::win::ScopedComPtr<IDWriteFontFace> font_face;
hr = gdi_interop->CreateFontFaceFromHdc(screen_dc, font_face.Receive());
if (FAILED(hr))
return hr;
LOGFONT converted_font = {0};
hr = gdi_interop->ConvertFontFaceToLOGFONT(font_face.get(), &converted_font);
if (SUCCEEDED(hr)) {
hr = font_collection->GetFontFromFontFace(font_face.get(), dwrite_font);
if (SUCCEEDED(hr)) {
wcscpy_s(font_info->lfFaceName, arraysize(font_info->lfFaceName),
converted_font.lfFaceName);
}
}
return hr;
}
// Returns a matching IDWriteFont for the |font_info| passed in. If we fail
// to find a matching font, then we return the IDWriteFont corresponding to
// the default font on the system.
// Returns S_OK on success.
// The contents of the LOGFONT pointer |font_info| may be modified on
// return.
HRESULT GetMatchingDirectWriteFont(LOGFONT* font_info,
int font_style,
IDWriteFactory* factory,
IDWriteFont** dwrite_font) {
// First try the GDI compat route to get a matching DirectWrite font.
// If that succeeds then we are good. If that fails then try and find a
// match from the DirectWrite font collection.
HRESULT hr = FindDirectWriteFontForLOGFONT(factory, font_info, dwrite_font);
if (SUCCEEDED(hr))
return hr;
// Get a matching font from the system font collection exposed by
// DirectWrite.
base::win::ScopedComPtr<IDWriteFontCollection> font_collection;
hr = factory->GetSystemFontCollection(font_collection.Receive());
if (FAILED(hr)) {
CHECK(false);
return hr;
}
// Steps as below:-
// This mirrors skia.
// 1. Attempt to find a DirectWrite font family based on the face name in the
// font. That may not work at all times, as the face name could be random
// GDI has its own font system where in it creates a font matching the
// characteristics in the LOGFONT structure passed into
// CreateFontIndirect. DirectWrite does not do that. If this succeeds then
// return the matching IDWriteFont from the family.
// 2. If step 1 fails then repeat with the default system font. This has the
// same limitations with the face name as mentioned above.
// 3. If step 2 fails then return the first family from the collection and
// use that.
base::win::ScopedComPtr<IDWriteFontFamily> font_family;
BOOL exists = FALSE;
uint32 index = 0;
hr = font_collection->FindFamilyName(font_info->lfFaceName, &index, &exists);
// If we fail to find a match then try fallback to the default font on the
// system. This is what skia does as well.
if (FAILED(hr) || (index == UINT_MAX) || !exists) {
NONCLIENTMETRICS metrics = {0};
metrics.cbSize = sizeof(metrics);
if (!SystemParametersInfoW(SPI_GETNONCLIENTMETRICS,
sizeof(metrics),
&metrics,
0)) {
CHECK(false);
return E_FAIL;
}
if (base::strncmp16(font_info->lfFaceName, metrics.lfMessageFont.lfFaceName,
arraysize(font_info->lfFaceName))) {
// First try the GDI compat route to get a matching DirectWrite font. If
// that succeeds we are good. If not find a matching font from the font
// collection.
wcscpy_s(font_info->lfFaceName, arraysize(font_info->lfFaceName),
metrics.lfMessageFont.lfFaceName);
hr = FindDirectWriteFontForLOGFONT(factory, font_info, dwrite_font);
if (SUCCEEDED(hr))
return hr;
// Best effort to find a matching font from the system font collection.
hr = font_collection->FindFamilyName(metrics.lfMessageFont.lfFaceName,
&index,
&exists);
}
}
if (index != UINT_MAX && exists) {
hr = font_collection->GetFontFamily(index, font_family.Receive());
} else {
// If we fail to find a matching font, then fallback to the first font in
// the list. This is what skia does as well.
hr = font_collection->GetFontFamily(0, font_family.Receive());
}
if (FAILED(hr)) {
CHECK(false);
return hr;
}
DWRITE_FONT_WEIGHT weight = (font_style & SkTypeface::kBold)
? DWRITE_FONT_WEIGHT_BOLD
: DWRITE_FONT_WEIGHT_NORMAL;
DWRITE_FONT_STRETCH stretch = DWRITE_FONT_STRETCH_NORMAL;
DWRITE_FONT_STYLE italic = (font_style & SkTypeface::kItalic)
? DWRITE_FONT_STYLE_ITALIC
: DWRITE_FONT_STYLE_NORMAL;
// The IDWriteFontFamily::GetFirstMatchingFont call fails on certain machines
// for fonts like MS UI Gothic, Segoe UI, etc. It is not clear why these
// fonts could be accessible to GDI and not to DirectWrite.
// The code below adds some debug fields to help track down these failures.
// 1. We get the matching font list for the font attributes passed in.
// 2. We get the font count in the family with a debug alias variable.
// 3. If GetFirstMatchingFont fails then we CHECK as before.
// Next step would be to remove the CHECKs in this function and fallback to
// GDI.
// http://crbug.com/434425
// TODO(ananta)
// Remove the GetMatchingFonts and related code here once we get to a stable
// state in canary.
base::win::ScopedComPtr<IDWriteFontList> matching_font_list;
hr = font_family->GetMatchingFonts(weight, stretch, italic,
matching_font_list.Receive());
uint32 matching_font_count = 0;
if (SUCCEEDED(hr))
matching_font_count = matching_font_list->GetFontCount();
hr = font_family->GetFirstMatchingFont(weight, stretch, italic,
dwrite_font);
if (FAILED(hr)) {
base::debug::Alias(&matching_font_count);
CHECK(false);
}
base::string16 font_name;
GetFamilyNameFromDirectWriteFont(*dwrite_font, &font_name);
wcscpy_s(font_info->lfFaceName, arraysize(font_info->lfFaceName),
font_name.c_str());
return hr;
}
} // namespace
namespace gfx {
// static
PlatformFontWin::HFontRef* PlatformFontWin::base_font_ref_;
// static
PlatformFontWin::AdjustFontCallback
PlatformFontWin::adjust_font_callback = nullptr;
PlatformFontWin::GetMinimumFontSizeCallback
PlatformFontWin::get_minimum_font_size_callback = NULL;
IDWriteFactory* PlatformFontWin::direct_write_factory_ = nullptr;
////////////////////////////////////////////////////////////////////////////////
// PlatformFontWin, public
PlatformFontWin::PlatformFontWin() : font_ref_(GetBaseFontRef()) {
}
PlatformFontWin::PlatformFontWin(NativeFont native_font) {
InitWithCopyOfHFONT(native_font);
}
PlatformFontWin::PlatformFontWin(const std::string& font_name,
int font_size) {
InitWithFontNameAndSize(font_name, font_size);
}
Font PlatformFontWin::DeriveFontWithHeight(int height, int style) {
DCHECK_GE(height, 0);
// Create a font with a height near that of the target height.
LOGFONT font_info;
GetObject(GetNativeFont(), sizeof(LOGFONT), &font_info);
font_info.lfHeight = height;
SetLogFontStyle(style, &font_info);
HFONT hfont = CreateFontIndirect(&font_info);
Font font(new PlatformFontWin(CreateHFontRef(hfont)));
// Respect the minimum font size constraint.
const int min_font_size = GetMinimumFontSize();
// Used to avoid shrinking the font and expanding it.
bool ran_shrink_loop = false;
// Iterate to find the largest font with a height <= |height|.
while ((font.GetHeight() > height) &&
(font.GetFontSize() >= min_font_size)) {
ran_shrink_loop = true;
Font derived_font = font.Derive(-1, style);
// Break the loop if the derived font is too small or hasn't shrunk at all.
if ((derived_font.GetFontSize() < min_font_size) ||
((derived_font.GetFontSize() == font.GetFontSize()) &&
(derived_font.GetHeight() == font.GetHeight())))
break;
font = derived_font;
}
while ((!ran_shrink_loop && font.GetHeight() <= height) ||
(font.GetFontSize() < min_font_size)) {
Font derived_font = font.Derive(1, style);
// Break the loop if the derived font is too large or hasn't grown at all.
if (((derived_font.GetHeight() > height) &&
(font.GetFontSize() >= min_font_size)) ||
((derived_font.GetFontSize() == font.GetFontSize()) &&
(derived_font.GetHeight() == font.GetHeight())))
break;
font = derived_font;
}
return font;
}
////////////////////////////////////////////////////////////////////////////////
// PlatformFontWin, PlatformFont implementation:
Font PlatformFontWin::DeriveFont(int size_delta, int style) const {
LOGFONT font_info;
GetObject(GetNativeFont(), sizeof(LOGFONT), &font_info);
const int requested_font_size = font_ref_->requested_font_size();
font_info.lfHeight = AdjustFontSize(-requested_font_size, size_delta);
SetLogFontStyle(style, &font_info);
HFONT hfont = CreateFontIndirect(&font_info);
return Font(new PlatformFontWin(CreateHFontRef(hfont)));
}
int PlatformFontWin::GetHeight() const {
return font_ref_->height();
}
int PlatformFontWin::GetBaseline() const {
return font_ref_->baseline();
}
int PlatformFontWin::GetCapHeight() const {
return font_ref_->cap_height();
}
int PlatformFontWin::GetExpectedTextWidth(int length) const {
return length * std::min(font_ref_->GetDluBaseX(),
font_ref_->ave_char_width());
}
int PlatformFontWin::GetStyle() const {
return font_ref_->style();
}
std::string PlatformFontWin::GetFontName() const {
return font_ref_->font_name();
}
std::string PlatformFontWin::GetActualFontNameForTesting() const {
// With the current implementation on Windows, HFontRef::font_name() returns
// the font name taken from the HFONT handle, but it's not the name that comes
// from the font's metadata. See http://crbug.com/327287
return font_ref_->font_name();
}
std::string PlatformFontWin::GetLocalizedFontName() const {
base::win::ScopedCreateDC memory_dc(CreateCompatibleDC(NULL));
if (!memory_dc.Get())
return GetFontName();
// When a font has a localized name for a language matching the system
// locale, GetTextFace() returns the localized name.
base::win::ScopedSelectObject font(memory_dc.Get(), font_ref_->hfont());
wchar_t localized_font_name[LF_FACESIZE];
int length = GetTextFace(memory_dc.Get(), arraysize(localized_font_name),
&localized_font_name[0]);
if (length <= 0)
return GetFontName();
return base::SysWideToUTF8(localized_font_name);
}
int PlatformFontWin::GetFontSize() const {
return font_ref_->font_size();
}
const FontRenderParams& PlatformFontWin::GetFontRenderParams() {
CR_DEFINE_STATIC_LOCAL(const gfx::FontRenderParams, params,
(gfx::GetFontRenderParams(gfx::FontRenderParamsQuery(), NULL)));
return params;
}
NativeFont PlatformFontWin::GetNativeFont() const {
return font_ref_->hfont();
}
// static
void PlatformFontWin::SetDirectWriteFactory(IDWriteFactory* factory) {
// We grab a reference on the DirectWrite factory. This reference is
// leaked, which is ok because skia leaks it as well.
factory->AddRef();
direct_write_factory_ = factory;
}
// static
void PlatformFontWin::GetTextMetricsForFont(HDC hdc,
HFONT font,
TEXTMETRIC* text_metrics) {
base::win::ScopedSelectObject scoped_font(hdc, font);
GetTextMetrics(hdc, text_metrics);
}
// static
int PlatformFontWin::GetFontSize(const LOGFONT& font_info) {
if (font_info.lfHeight < 0)
return -font_info.lfHeight;
base::win::ScopedGetDC screen_dc(NULL);
base::win::ScopedGDIObject<HFONT> font(CreateFontIndirect(&font_info));
TEXTMETRIC font_metrics = {0};
PlatformFontWin::GetTextMetricsForFont(screen_dc, font, &font_metrics);
return font_metrics.tmAscent;
}
////////////////////////////////////////////////////////////////////////////////
// Font, private:
void PlatformFontWin::InitWithCopyOfHFONT(HFONT hfont) {
DCHECK(hfont);
LOGFONT font_info;
GetObject(hfont, sizeof(LOGFONT), &font_info);
font_ref_ = CreateHFontRef(CreateFontIndirect(&font_info));
}
void PlatformFontWin::InitWithFontNameAndSize(const std::string& font_name,
int font_size) {
HFONT hf = ::CreateFont(-font_size, 0, 0, 0, FW_DONTCARE, FALSE, FALSE, FALSE,
DEFAULT_CHARSET,
OUT_DEFAULT_PRECIS,
CLIP_DEFAULT_PRECIS,
DEFAULT_QUALITY,
DEFAULT_PITCH | FF_DONTCARE,
base::UTF8ToUTF16(font_name).c_str());
font_ref_ = CreateHFontRef(hf);
}
// static
PlatformFontWin::HFontRef* PlatformFontWin::GetBaseFontRef() {
if (base_font_ref_ == NULL) {
NONCLIENTMETRICS_XP metrics;
base::win::GetNonClientMetrics(&metrics);
if (adjust_font_callback)
adjust_font_callback(&metrics.lfMessageFont);
metrics.lfMessageFont.lfHeight =
AdjustFontSize(metrics.lfMessageFont.lfHeight, 0);
HFONT font = CreateFontIndirect(&metrics.lfMessageFont);
DLOG_ASSERT(font);
base_font_ref_ = PlatformFontWin::CreateHFontRef(font);
// base_font_ref_ is global, up the ref count so it's never deleted.
base_font_ref_->AddRef();
}
return base_font_ref_;
}
PlatformFontWin::HFontRef* PlatformFontWin::CreateHFontRef(HFONT font) {
TEXTMETRIC font_metrics;
{
base::win::ScopedGetDC screen_dc(NULL);
gfx::ScopedSetMapMode mode(screen_dc, MM_TEXT);
GetTextMetricsForFont(screen_dc, font, &font_metrics);
}
if (direct_write_factory_)
return CreateHFontRefFromSkia(font, font_metrics);
return CreateHFontRefFromGDI(font, font_metrics);
}
PlatformFontWin::HFontRef* PlatformFontWin::CreateHFontRefFromGDI(
HFONT font,
const TEXTMETRIC& font_metrics) {
const int height = std::max<int>(1, font_metrics.tmHeight);
const int baseline = std::max<int>(1, font_metrics.tmAscent);
const int cap_height =
std::max<int>(1, font_metrics.tmAscent - font_metrics.tmInternalLeading);
const int ave_char_width = std::max<int>(1, font_metrics.tmAveCharWidth);
const int font_size =
std::max<int>(1, font_metrics.tmHeight - font_metrics.tmInternalLeading);
int style = 0;
if (font_metrics.tmItalic)
style |= Font::ITALIC;
if (font_metrics.tmUnderlined)
style |= Font::UNDERLINE;
if (font_metrics.tmWeight >= kTextMetricWeightBold)
style |= Font::BOLD;
return new HFontRef(font, font_size, height, baseline, cap_height,
ave_char_width, style);
}
// static
PlatformFontWin::HFontRef* PlatformFontWin::CreateHFontRefFromSkia(
HFONT gdi_font,
const TEXTMETRIC& font_metrics) {
LOGFONT font_info = {0};
GetObject(gdi_font, sizeof(LOGFONT), &font_info);
// If the font height is passed in as 0, assume the height to be -1 to ensure
// that we return the metrics for a 1 point font.
// If the font height is positive it represents the rasterized font's cell
// height. Calculate the actual height accordingly.
if (font_info.lfHeight > 0) {
font_info.lfHeight =
font_metrics.tmInternalLeading - font_metrics.tmHeight;
} else if (font_info.lfHeight == 0) {
font_info.lfHeight = -1;
}
int skia_style = SkTypeface::kNormal;
if (font_info.lfWeight >= FW_SEMIBOLD &&
font_info.lfWeight <= FW_ULTRABOLD) {
skia_style |= SkTypeface::kBold;
}
if (font_info.lfItalic)
skia_style |= SkTypeface::kItalic;
// Skia does not return all values we need for font metrics. For e.g.
// the cap height which indicates the height of capital letters is not
// returned even though it is returned by DirectWrite.
// TODO(ananta)
// Fix SkScalerContext_win_dw.cpp to return all metrics we need from
// DirectWrite and remove the code here which retrieves metrics from
// DirectWrite to calculate the cap height.
base::win::ScopedComPtr<IDWriteFont> dwrite_font;
HRESULT hr = GetMatchingDirectWriteFont(&font_info,
skia_style,
direct_write_factory_,
dwrite_font.Receive());
if (FAILED(hr)) {
CHECK(false);
return nullptr;
}
DWRITE_FONT_METRICS dwrite_font_metrics = {0};
dwrite_font->GetMetrics(&dwrite_font_metrics);
skia::RefPtr<SkTypeface> skia_face = skia::AdoptRef(
SkTypeface::CreateFromName(
base::SysWideToUTF8(font_info.lfFaceName).c_str(),
static_cast<SkTypeface::Style>(skia_style)));
gfx::FontRenderParams font_params =
gfx::GetFontRenderParams(gfx::FontRenderParamsQuery(), nullptr);
SkFontHost::SetSubpixelOrder(
gfx::FontRenderParams::SubpixelRenderingToSkiaLCDOrder(
font_params.subpixel_rendering));
SkFontHost::SetSubpixelOrientation(
gfx::FontRenderParams::SubpixelRenderingToSkiaLCDOrientation(
font_params.subpixel_rendering));
SkPaint paint;
paint.setAntiAlias(font_params.antialiasing);
paint.setTypeface(skia_face.get());
paint.setTextSize(-font_info.lfHeight);
SkPaint::FontMetrics skia_metrics;
paint.getFontMetrics(&skia_metrics);
// The calculations below are similar to those in the CreateHFontRef
// function. The height, baseline and cap height are rounded up to ensure
// that they match up closely with GDI.
const int height = std::ceil(skia_metrics.fDescent - skia_metrics.fAscent);
const int baseline = std::max<int>(1, std::ceil(-skia_metrics.fAscent));
const int cap_height = std::ceil(paint.getTextSize() *
static_cast<double>(dwrite_font_metrics.capHeight) /
dwrite_font_metrics.designUnitsPerEm);
// The metrics retrieved from skia don't have the average character width. In
// any case if we get the average character width from skia then use that or
// the average character width in the TEXTMETRIC structure.
// TODO(ananta): Investigate whether it is possible to retrieve this value
// from DirectWrite.
const int ave_char_width =
skia_metrics.fAvgCharWidth == 0 ? font_metrics.tmAveCharWidth
: skia_metrics.fAvgCharWidth;
int style = 0;
if (skia_style & SkTypeface::kItalic)
style |= Font::ITALIC;
if (font_info.lfUnderline)
style |= Font::UNDERLINE;
if (font_info.lfWeight >= kTextMetricWeightBold)
style |= Font::BOLD;
// DirectWrite may have substituted the GDI font name with a fallback
// font. Ensure that it is updated here.
DeleteObject(gdi_font);
gdi_font = ::CreateFontIndirect(&font_info);
return new HFontRef(gdi_font, -font_info.lfHeight, height, baseline,
cap_height, ave_char_width, style);
}
PlatformFontWin::PlatformFontWin(HFontRef* hfont_ref) : font_ref_(hfont_ref) {
}
PlatformFontWin::~PlatformFontWin() {
}
////////////////////////////////////////////////////////////////////////////////
// PlatformFontWin::HFontRef:
PlatformFontWin::HFontRef::HFontRef(HFONT hfont,
int font_size,
int height,
int baseline,
int cap_height,
int ave_char_width,
int style)
: hfont_(hfont),
font_size_(font_size),
height_(height),
baseline_(baseline),
cap_height_(cap_height),
ave_char_width_(ave_char_width),
style_(style),
dlu_base_x_(-1),
requested_font_size_(font_size) {
DLOG_ASSERT(hfont);
LOGFONT font_info;
GetObject(hfont_, sizeof(LOGFONT), &font_info);
font_name_ = base::UTF16ToUTF8(base::string16(font_info.lfFaceName));
// Retrieve the font size from the GetTextMetrics API instead of referencing
// it from the LOGFONT structure. This is because the height as reported by
// the LOGFONT structure is not always correct. For small fonts with size 1
// the LOGFONT structure reports the height as -1, while the actual font size
// is different. (2 on my XP machine).
base::win::ScopedGetDC screen_dc(NULL);
TEXTMETRIC font_metrics = {0};
PlatformFontWin::GetTextMetricsForFont(screen_dc, hfont_, &font_metrics);
requested_font_size_ = font_metrics.tmHeight - font_metrics.tmInternalLeading;
}
int PlatformFontWin::HFontRef::GetDluBaseX() {
if (dlu_base_x_ != -1)
return dlu_base_x_;
dlu_base_x_ = GetAverageCharWidthInDialogUnits(hfont_);
return dlu_base_x_;
}
// static
int PlatformFontWin::HFontRef::GetAverageCharWidthInDialogUnits(
HFONT gdi_font) {
base::win::ScopedGetDC screen_dc(NULL);
base::win::ScopedSelectObject font(screen_dc, gdi_font);
gfx::ScopedSetMapMode mode(screen_dc, MM_TEXT);
// Yes, this is how Microsoft recommends calculating the dialog unit
// conversions. See: http://support.microsoft.com/kb/125681
SIZE ave_text_size;
GetTextExtentPoint32(screen_dc,
L"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz",
52, &ave_text_size);
int dlu_base_x = (ave_text_size.cx / 26 + 1) / 2;
DCHECK_NE(dlu_base_x, -1);
return dlu_base_x;
}
PlatformFontWin::HFontRef::~HFontRef() {
DeleteObject(hfont_);
}
////////////////////////////////////////////////////////////////////////////////
// PlatformFont, public:
// static
PlatformFont* PlatformFont::CreateDefault() {
return new PlatformFontWin;
}
// static
PlatformFont* PlatformFont::CreateFromNativeFont(NativeFont native_font) {
return new PlatformFontWin(native_font);
}
// static
PlatformFont* PlatformFont::CreateFromNameAndSize(const std::string& font_name,
int font_size) {
return new PlatformFontWin(font_name, font_size);
}
} // namespace gfx