Visão Geral de ClearType
Este tópico fornece uma visão geral sobre o Microsoft ClearType tecnologia encontrada na Windows Presentation Foundation (WPF).
Este tópico contém as seguintes seções.
- Technology Overview
- Sub-pixel Positioning
- Y-Direction Antialiasing
- Hardware Acceleration
- Further Information
- Tópicos relacionados
Technology Overview
ClearTypeé uma tecnologia de software desenvolvida pela Microsoft que melhora a legibilidade do texto existentes LCDs (telas de cristal), como telas de laptop, Pocket PC telas e monitores de tela plana. ClearTypeWorks, acessando os elementos de faixa de cor vertical individuais em cada pixel de uma tela de LCD. Before ClearType, the smallest level of detail that a computer could display was a single pixel, but with ClearType running on an LCD monitor, we can now display features of text as small as a fraction of a pixel in width. The extra resolution increases the sharpness of the tiny details in text display, making it much easier to read over long durations.
O ClearType disponível em Windows Presentation Foundation (WPF) é a última geração de ClearType que tem vários aperfeiçoamentos sobre versão encontrados em Microsoft Windows Graphics Device Interface (GDI).
Sub-pixel Positioning
A significant improvement over the previous version of ClearType is the use of sub-pixel positioning. Ao contrário do ClearType implementação encontrada no GDI, o ClearType encontrado no Windows Presentation Foundation (WPF) permite que os glifos para iniciar o pixel e não apenas o limite de início do pixel. Because of this extra resolution in positioning glyphs, the spacing and proportions of the glyphs is more precise and consistent.
The following two examples show how glyphs may begin on any sub-pixel boundary when sub-pixel positioning is used. The example on the left is rendered using the earlier version of the ClearType renderer, which did not employ sub-pixel positioning. The example on the right is rendered using the new version of the ClearType renderer, using sub-pixel positioning. Observe como cada e e l na imagem à direita é renderizado ligeiramente diferente porque cada um começa em um sub-pixel diferente. When viewing the text at its normal size on the screen, this difference is not noticeable because of the high contrast of the glyph image. Isso só é possível por causa de filtragem de cores sofisticado que é incorporado em ClearType.
Text displayed with earlier and later versions of ClearType
.png "Texto exibido com duas versões de ClearType")
The following two examples compare output from the earlier ClearType renderer with the new version of the ClearType renderer. The subpixel positioning, shown on the right, greatly improves the spacing of type on screen, especially at small sizes where the difference between a sub-pixel and a whole pixel represents a significant proportion of glyph width. Note that spacing between the letters is more even in the second image. The cumulative benefit of sub-pixel positioning to the overall appearance of a screen of text is greatly increased, and represents a significant evolution in ClearType technology.
Text with earlier and later versions of ClearType
.png "Texto exibido com a versão anterior de ClearType")
Y-Direction Antialiasing
Another improvement of ClearType in Windows Presentation Foundation (WPF) is y-direction anti-aliasing. O ClearType em GDI sem direção y suavização de serrilhado fornece a melhor resolução do eixo x mas não o eixo y. On the tops and bottoms of shallow curves, the jagged edges detract from its readability.
The following example shows the effect of having no y-direction antialiasing. In this case, the jagged edges on the top and bottom of the letter are apparent.
Text with jagged edges on shallow curves
.png "Texto com bordas irregulares em curvas superficiais")
ClearType in Windows Presentation Foundation (WPF) provides antialiasing on the y-direction level to smooth out any jagged edges. This is particularly important for improving the readability of East Asian languages where ideographs have an almost equal amount of horizontal and vertical shallow curves.
The following example shows the effect of y-direction antialiasing. In this case, the top and bottom of the letter show a smooth curve.
Text with ClearType y-direction antialiasing
.png "Texto com suavização e direção y ClearType")
Hardware Acceleration
ClearTypeem Windows Presentation Foundation (WPF) pode tirar proveito de aceleração de hardware para melhorar o desempenho e reduzir CPU carga e o sistema de memória requisitos. By using the pixel shaders and video memory of a graphics card, ClearType provides faster rendering of text, particularly when animation is used.
ClearType in Windows Presentation Foundation (WPF) does not modify the system-wide ClearType settings. Desabilitando ClearType em Windows define Windows Presentation Foundation (WPF) antialiasing modo tons de cinza. Além disso, ClearType na Windows Presentation Foundation (WPF) não modificar as configurações da PowerToy de sintonizador ClearType.
One of the Windows Presentation Foundation (WPF) architectural design decisions is to have resolution independent layout better support higher resolution DPI monitors, which are becoming more widespread. This has the consequence of Windows Presentation Foundation (WPF) not supporting aliased text rendering or the bitmaps in some East Asian fonts because they are both resolution dependent.
Further Information
Sintonizador ClearType PowerToy