/// <summary>
/// Gets a device capability represented as an array
/// </summary>
/// <param name="capability">Capability to retrieve</param>
/// <returns>value of capability specified in capability argument</returns>
private T[] GetArrayCapability <T>(DeviceCapability capability, ReadArray <T> readArray, int itemByteSize)
{
uint numOutputs = UnsafeNativeMethods.DeviceCapabilitiesW(this._deviceName, this._portName, capability, SafeMemoryHandle.Null, this._devMode);
if (numOutputs < 1)
{
return(Array.Empty <T>());
}
HGlobalBuffer buffer = new HGlobalBuffer((int)(numOutputs * itemByteSize));
try
{
numOutputs = UnsafeNativeMethods.DeviceCapabilitiesW(this._deviceName, this._portName, capability, buffer.Handle, this._devMode);
if (numOutputs >= 0)
{
return(readArray(buffer, itemByteSize));
}
}
finally
{
buffer.Release();
}
return(null);
}
///<summary>
/// Executes an action delegate on an unmanaged buffer representing printer information
///</summary>
///<param name="dwLevel">Level of printer information to process</param>
///<param name="action">Delegate that processes printer information</param>
///<returns>False if tha call fails</returns>
private bool GetPrinterW(uint dwLevel, Action <HGlobalBuffer> action)
{
uint dwNeeded = 0;
UnsafeNativeMethods.GetPrinterW(this._deviceHandle, dwLevel, SafeMemoryHandle.Null, dwNeeded, ref dwNeeded);
if (dwNeeded > 0)
{
HGlobalBuffer pPrinterBuffer = new HGlobalBuffer((int)dwNeeded);
try
{
if (UnsafeNativeMethods.GetPrinterW(this._deviceHandle, dwLevel, pPrinterBuffer.Handle, dwNeeded, ref dwNeeded))
{
action(pPrinterBuffer);
return(true);
}
}
finally
{
pPrinterBuffer.Release();
}
}
return(false);
}