/// <summary>
/// Given a text position and whether the caret is on the leading or trailing
/// edge of that position, this returns the corresponding coordinate (in DIPs)
/// relative to the top-left of the layout box. This is most useful for drawing
/// the caret's current position, but it could also be used to anchor an IME to the
/// typed text or attach a floating menu near the point of interest. It may also be
/// used to programmatically obtain the geometry of a particular text position
/// for UI automation.
/// </summary>
/// <param name="textPosition">Text position to get the coordinate of.</param>
/// <param name="isTrailingHit">Flag indicating whether the location is of the leading or the trailing side of the specified text position. </param>
/// <param name="pointX">Output caret X, relative to the top-left of the layout box.</param>
/// <param name="pointY">Output caret Y, relative to the top-left of the layout box.</param>
/// <param name="hitTestMetrics">Output geometry fully enclosing the specified text position.</param>
/// <returns>
/// Standard HRESULT error code.
/// </returns>
/// <remarks>
/// <code>
/// STDMETHOD(HitTestTextPosition)(
/// UINT32 textPosition,
/// BOOL isTrailingHit,
/// _Out_ FLOAT* pointX,
/// _Out_ FLOAT* pointY,
/// _Out_ DWRITE_HIT_TEST_METRICS* hitTestMetrics
/// ) PURE;
/// </code>
/// When drawing a caret at the returned X,Y, it should be centered on X
/// and drawn from the Y coordinate down. The height will be the size of the
/// hit-tested text (which can vary in size within a line).
/// Reading direction also affects which side of the character the caret is drawn.
/// However, the returned X coordinate will be correct for either case.
/// You can get a text length back that is larger than a single character.
/// This happens for complex scripts when multiple characters form a single cluster,
/// when diacritics join their base character, or when you test a surrogate pair.
/// </remarks>
private void HitTestTextPosition(uint textPosition, bool isTrailingHit,
out float pointX, out float pointY, out HitTestMetrics hitTestMetrics)
{
var hr = hitTestTextPosition(comObject, textPosition, isTrailingHit, out pointX, out pointY,
out hitTestMetrics);
Marshal.ThrowExceptionForHR(hr);
}
/// <summary>
/// Given a coordinate (in DIPs) relative to the top-left of the layout box,
/// this returns the corresponding hit-test metrics of the text string where
/// the hit-test has occurred. This is useful for mapping mouse clicks to caret
/// positions. When the given coordinate is outside the text string, the function
/// sets the output value *isInside to false but returns the nearest character
/// position.
/// </summary>
/// <param name="pointX">X coordinate to hit-test, relative to the top-left location of the layout box.</param>
/// <param name="pointY">Y coordinate to hit-test, relative to the top-left location of the layout box.</param>
/// <param name="isTrailingHit">Output flag indicating whether the hit-test location is at the leading or the trailing
/// side of the character. When the output *isInside value is set to false, this value is set according to the output
/// *position value to represent the edge closest to the hit-test location. </param>
/// <param name="isInside">Output flag indicating whether the hit-test location is inside the text string.
/// When false, the position nearest the text's edge is returned.</param>
/// <param name="hitTestMetrics">Output geometry fully enclosing the hit-test location. When the output *isInside value
/// is set to false, this structure represents the geometry enclosing the edge closest to the hit-test location.</param>
/// <returns>
/// Standard HRESULT error code.
/// </returns>
/// <remarks>
/// <code>
/// STDMETHOD(HitTestPoint)(
/// FLOAT pointX,
/// FLOAT pointY,
/// _Out_ BOOL* isTrailingHit,
/// _Out_ BOOL* isInside,
/// _Out_ DWRITE_HIT_TEST_METRICS* hitTestMetrics
/// ) PURE;
/// </code>
/// </remarks>
private void HitTestPoint(float pointX, float pointY,
out bool isTrailingHit, out bool isInside, out HitTestMetrics hitTestMetrics)
{
var hr = hitTestPoint(comObject, pointX, pointY, out isTrailingHit, out isInside, out hitTestMetrics);
Marshal.ThrowExceptionForHR(hr);
}
