tailieunhanh - Symbian OS C++ for Mobile Phones VOL 1 PHẦN 7

Cập nhật xem iAppView- DrawNow ();} trình tự bình thường của chế biến ở đây là tôi gọi thoại (bằng cách sử dụng cú pháp ngắn gọn được bao phủ trong Chương 10), viết các tập tin, và vẽ lại xem ứng dụng để phản ánhiText giá trị. Nếu WriteFileL () lá, tôi xử lý nó bằng cách xóa iText và thiết lập con trỏ của nó là 0. | The influence of target devices on your code is even greater when the devices are relatively limited in CPU power and display resolution. With high-resolution displays and near-infinite CPU power you can render everything with no thought for rounding errors scale and so on. With small displays slower CPUs and no floating-point processor you have to take much more care in both graphical design and programming. In a map application zooming introduces considerations not only of scaling but also of visibility. In a high-level view of the map you want to see any coastline a few major cities big rivers and any borders. In a zoomed-in view of a city you want to see district names underground train stations public buildings and so on. In the high-level view you wouldn t try to draw these details at small scale you would omit them altogether. And this omission is device- dependent you can include more minor features in a printed view than in an on-screen view at the same zoom level because most printers have higher resolution than a screen. There are plenty of other complications with maps such as aligning labels with features and transverse scaling of linear elements such as roads - and many other applications share these considerations. Fortunately you don t usually edit maps on a handheld device so there isn t the need for very quick reformatting code that there is with word processors. As a result there may actually be better code sharing between printer and screen views. GUI Systems Up to this point in the chapter we have been looking at size and device-independence of graphical applications. Now we will look at the smartphone independence of the GUI systems supporting these graphical applications on mobile phones. The GUI determines the appearance and the interactive mechanisms of a smartphone the look-and-feel . These are clearly going to vary between smartphones the GUI is like the applications that use it highly device-dependent. This section is divided into a