以编程方式更改 Mac 显示屏亮度

Question

如何从 cocoa 应用程序更改 Mac 显示屏亮度？

Answer 1

CGDisplayIOServicePort 是 在 OS 10.9 中已弃用 - 因此您必须使用 IOServiceGetMatchingServices 来获取 IODisplaySetFloatParameter 的服务参数。这是一个基本函数，用于查找名为“display”的服务并更改其亮度。

- (void) setBrightnessTo: (float) level
{

    io_iterator_t iterator;
    kern_return_t result = IOServiceGetMatchingServices(kIOMasterPortDefault,
                                                        IOServiceMatching("IODisplayConnect"),
                                                        &iterator);

    // If we were successful
    if (result == kIOReturnSuccess)
    {
        io_object_t service;
        while ((service = IOIteratorNext(iterator))) {
            IODisplaySetFloatParameter(service, kNilOptions, CFSTR(kIODisplayBrightnessKey), level);

            // Let the object go
            IOObjectRelease(service);

            return;
        }
    }
}

在 Swift 中（通过 @Dov）：（

private func setBrightnessLevel(level: Float) {
    var iterator: io_iterator_t = 0

    let result = IOServiceGetMatchingServices(kIOMasterPortDefault,
                                              IOServiceMatching("IODisplayConnect").takeUnretainedValue(),
                                              &iterator)

    if result == kIOReturnSuccess {
        var service: io_object_t = 1

        for ;; {
            service = IOIteratorNext(iterator)

            if service == 0 {
                break
            }

            IODisplaySetFloatParameter(service, 0, kIODisplayBrightnessKey, level)
            IOObjectRelease(service)
        }
    }
}

代码是 当然是开源的）

Answer 2

扩展亚历克斯的答案：

在带有 Swift3 的 Xcode8 beta3 中，代码更加精简。

 private func setBrightness(level: Float) {
    let service = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("IODisplayConnect"))

    IODisplaySetFloatParameter(service, 0, kIODisplayBrightnessKey, level)
    IOObjectRelease(service)
}

Answer 3

来自 Alec Jacobson 的亮度菜单源代码：

- (void) set_brightness:(float) new_brightness {
CGDirectDisplayID display[kMaxDisplays];
CGDisplayCount numDisplays;
CGDisplayErr err;
err = CGGetActiveDisplayList(kMaxDisplays, display, &numDisplays);

if (err != CGDisplayNoErr)
    printf("cannot get list of displays (error %d)\n",err);
for (CGDisplayCount i = 0; i < numDisplays; ++i) {
    CGDirectDisplayID dspy = display[i];
    CFDictionaryRef originalMode = CGDisplayCurrentMode(dspy);
    if (originalMode == NULL)
        continue;
            io_service_t service = CGDisplayIOServicePort(dspy);

    float brightness;
    err= IODisplayGetFloatParameter(service, kNilOptions, kDisplayBrightness,
                                    &brightness);
    if (err != kIOReturnSuccess) {
        fprintf(stderr,
                "failed to get brightness of display 0x%x (error %d)",
                (unsigned int)dspy, err);
        continue;
    }

    err = IODisplaySetFloatParameter(service, kNilOptions, kDisplayBrightness,
                                     new_brightness);
    if (err != kIOReturnSuccess) {
        fprintf(stderr,
                "Failed to set brightness of display 0x%x (error %d)",
                 (unsigned int)dspy, err);
        continue;
    }
}       

}

Answer 4

在 Xcode 8 beta 6 中无法编译：

IODisplaySetFloatParameter(service, 0, kIODisplayBrightnessKey, level)

无法将“String”类型的值转换为预期的参数类型“CFString！”

所以让我们来投射它：

IODisplaySetFloatParameter(service, 0, kIODisplayBrightnessKey as CFString!, level)