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// Copyright (c) 2010 The Chromium OS 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 <string>
#include <vector>
#include "base/basictypes.h"
namespace monitor_reconfig {
// ResolutionSelector takes the sets of resolutions supported by the
// built-in and external displays as input and attempts to choose a shared
// resolution that will work well on both devices.
class ResolutionSelector {
// A single mode supported by a device, equivalent to the XRRModeInfo
// struct.
struct Mode {
Mode(int width, int height, std::string name, int id)
: width(width),
id(id) {
: width(0),
id(0) {
// Mode's dimensions.
int width;
int height;
// Mode's name from XRandR. This uniquely describes the mode and can
// be used to set the devices's resolution later.
std::string name;
// The mode id, used for setting this mode.
unsigned id;
// Maximum screen size for the external output at which we assume that
// it's a projector (as opposed to a monitor) and try to find a size that
// will also fit on the LCD display. Above this, we just use the
// external output's maximum resolution, even if it doesn't fit on the
// LCD.
static const int kMaxProjectorPixels;
ResolutionSelector() {}
~ResolutionSelector() {}
// Comparator used to sort Mode objects.
// Returns true if |mode_a| has more pixels than |mode_b| and false otherwise.
class ModeResolutionComparator {
bool operator()(const Mode& mode_a, const Mode& mode_b) const {
return mode_a.width * mode_a.height > mode_b.width * mode_b.height;
// Find the "best" resolutions for various outputs.
// Returns the modes for both screens and the total screen resolution.
bool FindBestResolutions(
const std::vector<Mode>& lcd_modes,
const std::vector<Mode>& external_modes,
Mode* lcd_resolution,
Mode* external_resolution,
Mode* screen_resolution);
// Find resolutions to use that are reasonably close together.
// |larger_device_modes| and |smaller_device_modes| should be sorted by
// descending resolution. We choose the highest resolution from
// |smaller_device_modes| and the lowest resolution from |larger_device_modes|
// that's at least as high as the resolution from the smaller device.
// |screen_resolution| gets set to |smaller_resolution| to avoid clipping.
bool FindNearestResolutions(
const std::vector<Mode>& larger_device_modes,
const std::vector<Mode>& smaller_device_modes,
Mode* larger_resolution,
Mode* smaller_resolution,
Mode* screen_resolution);
} // namespace monitor_reconfig