mirror of
https://github.com/flutter/flutter.git
synced 2026-02-20 02:29:02 +08:00
72 lines
2.3 KiB
C++
72 lines
2.3 KiB
C++
// Copyright 2014 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/display/util/display_util.h"
|
|
|
|
#include "base/logging.h"
|
|
|
|
namespace ui {
|
|
|
|
namespace {
|
|
|
|
// A list of bogus sizes in mm that should be ignored.
|
|
// See crbug.com/136533. The first element maintains the minimum
|
|
// size required to be valid size.
|
|
const int kInvalidDisplaySizeList[][2] = {
|
|
{40, 30},
|
|
{50, 40},
|
|
{160, 90},
|
|
{160, 100},
|
|
};
|
|
|
|
// The DPI threshold to detect high density screen.
|
|
// Higher DPI than this will use device_scale_factor=2.
|
|
const unsigned int kHighDensityDPIThresholdSmall = 170;
|
|
|
|
// The HiDPI threshold for large (usually external) monitors. Lower threshold
|
|
// makes sense for large monitors, because such monitors should be located
|
|
// farther from the user's face usually. See http://crbug.com/348279
|
|
const unsigned int kHighDensityDPIThresholdLarge = 150;
|
|
|
|
// The width threshold in mm for "large" monitors.
|
|
const int kLargeDisplayWidthThresholdMM = 500;
|
|
|
|
// 1 inch in mm.
|
|
const float kInchInMm = 25.4f;
|
|
|
|
} // namespace
|
|
|
|
bool IsDisplaySizeBlackListed(const gfx::Size& physical_size) {
|
|
// Ignore if the reported display is smaller than minimum size.
|
|
if (physical_size.width() <= kInvalidDisplaySizeList[0][0] ||
|
|
physical_size.height() <= kInvalidDisplaySizeList[0][1]) {
|
|
VLOG(1) << "Smaller than minimum display size";
|
|
return true;
|
|
}
|
|
for (size_t i = 1; i < arraysize(kInvalidDisplaySizeList); ++i) {
|
|
const gfx::Size size(kInvalidDisplaySizeList[i][0],
|
|
kInvalidDisplaySizeList[i][1]);
|
|
if (physical_size == size) {
|
|
VLOG(1) << "Black listed display size detected:" << size.ToString();
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
float GetScaleFactor(const gfx::Size& physical_size_in_mm,
|
|
const gfx::Size& screen_size_in_pixels) {
|
|
if (IsDisplaySizeBlackListed(physical_size_in_mm))
|
|
return 1.0f;
|
|
|
|
const unsigned int dpi = static_cast<unsigned int>(
|
|
kInchInMm * screen_size_in_pixels.width() / physical_size_in_mm.width());
|
|
const unsigned int threshold =
|
|
(physical_size_in_mm.width() >= kLargeDisplayWidthThresholdMM) ?
|
|
kHighDensityDPIThresholdLarge : kHighDensityDPIThresholdSmall;
|
|
return (dpi > threshold) ? 2.0f : 1.0f;
|
|
}
|
|
|
|
} // namespace ui
|