Android：运行图的滚动条
我有一个自定义视图，它绘制一个运行图 - 某个幅度与时间的关系。现在我想为此实现一个自定义滚动条，以便我可以查看屏幕外的过去数据。数据可供我使用。我只需要用户选择 %offset 。
任何有关实施的帮助/建议都会很有帮助。
我的自定义视图的 onDraw 方法中的代码片段
public void onDraw(Canvas canvas) {
int totalpts = data.size();
scale = getWidth() / (float) maxpoints;
List<Data> display = new ArrayList<Data>();
int initial = 1;
if (totalpts > maxpoints) {
initial = totalpts - maxpoints;
display = data.subList(initial, data.size() - 1);
} else {
display = data;
}
int size = display.size();
Data start = null;
float x1 = 0, x2 = 0, x = 0;
if (size > 1) {
x1 = getWidth();
start = display.get(display.size() - 1);
for (int i = display.size() - 1; i >= 0; i--) {
Data stop = display.get(i);
x = x1;
x1 -= (stop.x * scale / 1000);
canvas.drawLine(x, start.Y, x1, stop.Y, paint1);
start = stop;
}
}
}
I've a custom view which draws a running graph - some magnitude versus time. Now I want to implement a custom scroll bar for this so that I can view past data which are offscreen. The data is available to me. I just need the %offset selection by the user.
Any help/suggestions on implementation would be v helpful.
Code Snippet from my Custom view's onDraw method
public void onDraw(Canvas canvas) {
int totalpts = data.size();
scale = getWidth() / (float) maxpoints;
List<Data> display = new ArrayList<Data>();
int initial = 1;
if (totalpts > maxpoints) {
initial = totalpts - maxpoints;
display = data.subList(initial, data.size() - 1);
} else {
display = data;
}
int size = display.size();
Data start = null;
float x1 = 0, x2 = 0, x = 0;
if (size > 1) {
x1 = getWidth();
start = display.get(display.size() - 1);
for (int i = display.size() - 1; i >= 0; i--) {
Data stop = display.get(i);
x = x1;
x1 -= (stop.x * scale / 1000);
canvas.drawLine(x, start.Y, x1, stop.Y, paint1);
start = stop;
}
}
}
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评论（1）
尝试将自定义控件放入 HorizonatalScrollView 中（假设您希望它滚动水平），否则使用 ScrollView），设置宽度控件为“WRAP_CONTENT”，HizontalScrollView为“FILL_PARENT”。如果没有看到自定义视图的代码，就很难知道是否需要对宽度计算进行一些修改才能使其正常工作。
Try putting your custom control inside a HorizonatalScrollView (assuming you want it to scroll horizontally), use ScrollView otherwise), setting the width of your control to "WRAP_CONTENT", and the HoizontalScrollView to "FILL_PARENT". Without seeing the code for your custom view, it's difficult to know whether you might need to do some tinkering with the width calculation to get this working.