You can use the for-in
loop as shown by others. However, you also have to make sure that the key you get is an actual property of an object, and doesn't come from the prototype.
Here is the snippet:
var p = {
"p1": "value1",
"p2": "value2",
"p3": "value3"
};
for (var key in p) {
if (p.hasOwnProperty(key)) {
console.log(key + " -> " + p[key]);
}
}
For-of with Object.keys() alternative:
var p = {
0: "value1",
"b": "value2",
key: "value3"
};
for (var key of Object.keys(p)) {
console.log(key + " -> " + p[key])
}
Notice the use of for-of
instead of for-in
, if not used it will return undefined on named properties, and Object.keys()
ensures the use of only the object's own properties without the whole prototype-chain properties
Using the new Object.entries()
method:
Note: This method is not supported natively by Internet Explorer. You may consider using a Polyfill for older browsers.
const p = {
"p1": "value1",
"p2": "value2",
"p3": "value3"
};
for (let [key, value] of Object.entries(p)) {
console.log(`${key}: ${value}`);
}
If you want the display dimensions in pixels you can use getSize
:
Display display = getWindowManager().getDefaultDisplay();
Point size = new Point();
display.getSize(size);
int width = size.x;
int height = size.y;
If you're not in an Activity
you can get the default Display
via WINDOW_SERVICE
:
WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
Display display = wm.getDefaultDisplay();
If you are in a fragment and want to acomplish this just use Activity.WindowManager (in Xamarin.Android) or getActivity().getWindowManager() (in java).
Before getSize
was introduced (in API level 13), you could use the getWidth
and getHeight
methods that are now deprecated:
Display display = getWindowManager().getDefaultDisplay();
int width = display.getWidth(); // deprecated
int height = display.getHeight(); // deprecated
For the use case, you're describing, however, a margin/padding in the layout seems more appropriate.
Another way is: DisplayMetrics
A structure describing general information about a display, such as its size, density, and font scaling. To access the DisplayMetrics members, initialize an object like this:
DisplayMetrics metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);
We can use widthPixels
to get information for:
"The absolute width of the display in pixels."
Example:
Log.d("ApplicationTagName", "Display width in px is " + metrics.widthPixels);
API level 30 update
final WindowMetrics metrics = windowManager.getCurrentWindowMetrics();
// Gets all excluding insets
final WindowInsets windowInsets = metrics.getWindowInsets();
Insets insets = windowInsets.getInsetsIgnoreVisibility(WindowInsets.Type.navigationBars()
| WindowInsets.Type.displayCutout());
int insetsWidth = insets.right + insets.left;
int insetsHeight = insets.top + insets.bottom;
// Legacy size that Display#getSize reports
final Rect bounds = metrics.getBounds();
final Size legacySize = new Size(bounds.width() - insetsWidth,
bounds.height() - insetsHeight);
Best Answer
cv::Mat
is preferred overIplImage
because it simplifies your codeThis assumes that you need to use the RGB values together. If you don't, you can uses cv::split to get each channel separately. See etarion's answer for the link with example.
Also, in my cases, you simply need the image in gray-scale. Then, you can load the image in grayscale and access it as an array of uchar.
UPDATE: Using split to get the 3 channels
UPDATE: Thanks to entarion for spotting the error I introduced when copying and pasting from the cv::Vec3b example.